MAH  7 1373 


LIBRARY  OF  THE 
UNIVERSITY  OF  ILLINOIS 
AT  URBANA-CHAMPAIGN 


595.1 

D25f 

1900 


Biology 


The  person  charging  this  material  is  re- 
sponsible for  its  return  to  the  library  from 
which  it  was  withdrawn  on  or  before  the 
Latest  Date  stamped  below. 

Theft,  mutilation,  and  underlining  of  books 
are  reasons  for  disciplinary  action  and  may 
result  in  dismissal  from  the  University. 

UNIVERSITY  OF  ILLINOIS  LIBRARY  AT  URBANA-CHAMPAIGN 


Digitized  by  the  Internet  Archive 
in  2016  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/formationofveget00darw_0 


SELECTED  WORKS  OF 
CHARLES  DARWIN 

* 

WESTMINSTER  EDITION 


D.  Appleton  & Company 


Charles  Darwin's  Study  in  his  Residence  at  Down. 
Kent  County,  England. 


THE  FORMATION 
OF  VEGETABLE 
MOULD 

THROUGH  THE  ACTION  OF  WORMS 

By  Charles  Darwin 


D.  APPLETON  AND  COMPANY 
NEW  YORK  AND  LONDON 


Authorized  Edition. 


Limited  to  one  thousand  copies , 
of  which  this  is  No 


Introduction 


CHAPTER  I. 

HABITS  OF  WORMS. 


Nature  of  the  sites  inhabited — Can  live  long  under  water 
— Nocturnal — Wander  about  at  night — Often  lie  close 
to  the  mouths  of  their  burrows,  and  are  thus  destroyed 
in  large  numbers  by  birds — -Structure — Do  not  possess 
eyes,  but  can  distinguish  between  light  and  darkness — 
Retreat  rapidly  when  brightly  illuminated,  not  by  a re- 
flex action — Power  of  attention — Sensitive  to  heat  and 
cold — Completely  deaf — Sensitive  to  vibrations  and  to 
touch — Feeble  power  of  smell — Taste — Mental  qualities 
— Nature  of  food — Omnivorous — Digestion — Leaves, 
before  being  swallowed,  moistened  with  a fluid  of  the 
nature  of  the  pancreatic  secretion — Extra-stomachal 
digestion — Calciferous  glands,  structure  of — Calcareous 
concretions  formed  in  the  anterior  pair  of  glands — The 
calcareous  matter  primarily  an  excretion,  but  second- 
arily serves  to  neutralise  the  acids  generated  during  the 
digestive  process  . . . , , .8- 

CHAPTER  II. 
habits  of  worms — continued. 

Manner  in  which  worms  seize  objects — Their  power  of  suc- 
tion— The  instinct  of  plugging  up  the  mouths  of  their 
burrows — Stones  piled  over  the  burrows — The  advan- 


IV 


CONTENTS. 


PAGE 

tages  thus  gained — Intelligence  shown  by  worms  in 
their  manner  of  plugging  up  their  burrows — Various 
kinds  of  leaves  and  other  objects  thus  used — Triangles 
of  paper — Summary  of  reasons  for  believing  that  worms 
exhibit  some  intelligence — Means  by  which  they  exca- 
vate their  burrows,  by  pushing  away  the  earth  and  swal- 
lowing it — Earth  also  swallowed  for  the  nutritious  mat- 
ter which  it  contains — Depth  to  which  worms  burrow, 
and  the  construction  of  their  burrows — Burrows  lined 
with  castings,  and  in  the  upper  part  with  leaves — The 
lowest  part  paved  with  little  stones  or  seeds — Manner 
in  which  the  castings  are  ejected — The  collapse  of  old 
burrows — Distribution  of  worms — Tower-like  castings 
in  Bengal — Gigantic  castings  on  the  Nilgiri  Mountains 
— Castings  ejected  in  all  countries  • . . 56-130 

CHAPTER  III. 

THE  AMOUNT  OF  FINE  EARTH  BROUGHT  UP  BY  WORMS  TO  THE 
SURFACE. 

Rate  at  which  various  objects  strewed  on  the  surface  of 
grass-fields  are  covered  up  by  the  castings  of  worms — 

The  burial  of  a paved  path — The  slow  subsidence  of 
great  stones  left  on  the  surface — The  number  of  worms 
which  live  within  a given  space — The  weight  of  earth 
ejected  from  a burrow,  and  from  all  the  burrows  within 
a given  space — The  thickness  of  the  layer  of  mould 
which  the  castings  on  a given  space  would  form  within 
a given  time  if  uniformly  spread  out — The  slow  rate  at 
which  mould  can  increase  to  a great  thickness — Con- 
clusion  131-177 

CHAPTER  IV. 

THE  PART  WHICH  WORMS  HAVE  PLAYED  IN  THE  BURIAL  OF 
ANCIENT  BUILDINGS. 

The  accumulation  of  rubbish  on  the  sites  of  great  cities 
independent  of  the  action  of  worms — The  burial  of  a 


CONTENTS. 


V 


Roman  villa  at  Abinger — The  floors  and  walls  pene- 
trated by  worms — Subsidence  of  a modern  pavement — 

The  buried  pavement  at  Beaulieu  Abbey — Roman  vil- 
las at  Chedworth  and  Brading — The  remains  of  the 
Roman  town  at  Silchester — The  nature  of  the  debris 
by  which  the  remains  are  covered — The  penetration  of 
the  tessellated  floors  and  walls  by  worms — Subsidence 
of  the  floors — Thickness  of  the  mould — The  old  Roman 
city  of  Wroxeter — Thickness  of  the  mould — Depth  of 
the  foundations  of  some  of  the  buildings — Conclu- 
sion   178-232 


CHAPTER  V. 

THE  ACTION  OF  WORMS  IN  THE  DENUDATION  OF  THE  LAND. 

Evidence  of  the  amount  of  denudation  which  the  land 
has  undergone — Subaerial  denudation — The  deposition 
of  dust — Vegetable  mould,  its  dark  colour  and  fine 
texture  largely  due  to  the  action  of  worms — The  dis- 
integration of  rocks  by  the  humus-acids — Similar  acids 
apparently  generated  within  the  bodies  of  worms — The 
action  of  these  acids  facilitated  by  the  continued  move- 
ment of  the  particles  of  earth — A thick  bed  of  mould 
checks  the  disintegration  of  the  underlying  soil  and 
rocks — Particles  of  stone  worn  or  triturated  in  the  giz- 
zards of  worms — Swallowed  stones  serve  as  millstones 
— The  levigated  state  of  the  castings — Fragments  of 
brick  in  the  castings  over  ancient  buildings  well  round- 
ed— The  triturating  power  of  worms  not  quite  insig- 
nificant under  a geological  point  of  view  . . 233-261 

CHAPTER  VI. 

THE  DENUDATION  OF  THE  LAND — continued . 

Denudation  aided  by  recently  ejected  castings  flowing  down 
inclined  grass-covered  surfaces — The  amount  of  earth 
which  annually  flows  downwards — The  effect  of  trop- 
ical rain  on  worm  castings — The  finest  particles  of  earth 


VI 


CONTENTS. 


washed  completely  away  from  castings — The  disinte- 
gration of  dried  castings  into  pellets,  and  their  rolling 
down  inclined  surfaces — The  formation  of  little  ledges 
on  hill-sides,  in  part  due  to  the  accumulation  of  disin- 
tegrated castings — Castings  blown  to  leeward  over  level 
land — An  attempt  to  estimate  the  amount  thus  blown 
— The  degradation  of  ancient  encampments  and  tumuli 
— The  preservation  of  the  crowns  and  furrows  on  land 
anciently  ploughed — The  formation  and  amount  of 
mould  over  the  Chalk  formation  ...»  262-307/ 


CHAPTER  VII. 

CONCLUSION. 


Summary  of  the  part  which  worms  have  played  in  the  his- 
tory of  the  world — Their  aid  in  the  disintegration  of 
rocks — In  the  denudation  of  the  land — In  the  preser- 
vation of  ancient  remains — In  the  preparation  of  the 
soil  for  the  growth  of  plants — Mental  powers  of  worms 
— Conclusion  . 308-316 


Index 


317-326 


THE 


FORMATION  OF  VEGETABLE  MOULD, 

THROUGH  THE  ACTION  OF  WORMS,  WITH 
OBSERVATIONS  ON  THEIR  HABITS. 


INTRODUCTION. 

The  share  which  worms  have  taken  in  the 
formation  pf  the  layer  of  vegetable  mould, 
which  covers  the  whole  surface  of  the  land 
in  every  moderately  humid  country,  is  the  sub- 
ject of  the  present  volume.  This  mould  is  gen- 
erally of  a blackish  colour  and  a few  inches  in 
thickness.  In  different  districts  it  differs  but 
little  in  appearance,  although  it  may  rest  on 
various  subsoils.  The  uniform  fineness  of  the 
particles  of  which  it  is  composed  is  one  of  its 
chief  characteristic  features;  and  this  may  be 
well  observed  in  any  gravelly  country,  where  a 
recently-ploughed  field  immediately  adjoins 


2 


INTRODUCTION. 


one  which  has  long  remained  undisturbed  for 
pasture,  and  where  the  vegetable  mould  is  ex- 
posed on  the  sides  of  a ditch  or  hole.  The 
subject  may  appear  an  insignificant  one,  but 
we  shall  see  that  it  possesses  some  interest; 
and  the  maxim  “ de  minimis  lex  non  curat,” 
does  not  apply  to  science.  Even  Elie  de  Beau- 
mont, who  generally  undervalues  small  agen- 
cies and  their  accumulated  effects,  remarks,* 
“ la  couche  tres-mince  de  la  terre  vegetale  est 
un  monument  d’une  haute  antiquite,  et,  par  le 
fait  de  sa  permanence,  un  objet  digne  d’oc- 
cuper  le  geologue,  et  capable  de  lui  fournir 
des  remarques  interessantes.”  Although  the 
superficial  layer  of  vegetable  mould  as  a whole 
no  doubt  is  of  the  highest  antiquity,  yet  in  re- 
gard to  its  permanence,  we  shall  hereafter  see 
reason  to  believe  that  its  component  particles 
are  in  most  cases  removed  at  not  a very  slow 
rate,  and  are  replaced  by  others  due  to  the  dis- 
integration of  the  underlying  materials. 

As  I was  led  to  keep  in  my  study  during 
many  months  worms  in  pots  filled  with  earth, 
I became  interested  in  them,  and  wished  to 

* “ Le9ons  de  Geologie  Pratique,”  tom.  i.  1845,  p.  140. 


INTRODUCTION. 


3 


learn  how  far  they  acted  consciously,  and  how 
much  mental  power  they  displayed.  I was 
the  more  desirous  to  learn  something  on  this 
head,  as  few  observations  of  this  kind  have 
been  made,  as  far  as  I know,  on  animals  so 
low  in  the  scale  of  organization  and  so  poorly 
provided  with  sense-organs,  as  are  earth- 
worms. 

In  the  year  1837,  a short  paper  was  read  by 
me  before  the  Geological  Society  of  London,* 
“ On  the  Formation  of  Mould/’  in  which  it 
was  shown  that  small  fragments  of  burnt  marl, 
cinders,  &c.,  which  had  been  thickly  strewed 
over  the  surface  of  several  meadows,  were 
found  after  a few  years  lying  at  the  depth  of 
some  inches  beneath  the  turf,  but  still  forming 
a layer.  This  apparent  sinking  of  superficial 
bodies  is  due,  as  was  first  suggested  to  me  by 
Mr.  Wedgwood  of  Maer  Hall  in  Staffordshire, 
to  the  large  quantity  of  fine  earth  continually 
brought  up  to  the  surface  by  worms  in  the 
form  of  castings.  These  castings  are  sooner 
or  later  spread  out  and  cover  up  any  object 

♦“Transactions  Geolog.  Soc.”  vol.  v.  p.  505.  Read  No- 
vember 1,  1837. 


4 


INTRODUCTION. 


left  on  the  surface.  I was  thus  led  to  conclude 
that  all  the  vegetable  mould  over  the  whole 
country  has  passed  many  times  through,  and 
will  again  pass  many  times  through,  the  intes- 
tinal canals  of  worms.  Hence  the  term  “ ani- 
mal mould  ” would  be  in  some  respects  more 
appropriate  than  that  commonly  used  of  “ veg- 
etable mould.” 

Ten  years  after  the  publication  of  my  paper, 
M.  D’Archiac,  evidently  influenced  by  the  doc- 
trines of  Elie  de  Beaumont,  wrote  about  my 
“ singuliere  theorie,”  and  objected  that  it 
could  apply  only  to  “ les  prairies  basses  et 
humides;  ” and  that  “les  terres  labourees,  les 
bois,  les  prairies  elevees,  n’apportent  aucune 
preuve  a l’appui  de  cette  maniere  de  voir.”  * 
But  M.  D’Archiac  must  have  thus  argued  from 
inner  consciousness  and  not  from  observation, 
for  worms  abound  to  an  extraordinary  degree 
in  kitchen  gardens  where  the  soil  is  contin- 
ually worked,  though  in  such  loose  soil  they 
generally  deposit  their  castings  in  any  open 
cavities  or  within  their  old  burrows  instead  of 
on  the  surface.  Von  Hensen  estimates  that 

* “ Histoire  des  progr&s  de  la  G6ologie,”  tom.  i.  1847,  p.  224. 


INTRODUCTION. 


5 


there  are  about  twice  as  many  worms  in  gar- 
dens as  in  corn-fields.*  With  respect  to  “ prai- 
ries elevees,”  I do  not  know  how  it  may  be  in 
France,  but  nowhere  in  England  have  I seen 
the  ground  so  thickly  covered  with  castings  as 
on  commons,  at  a height  of  several  hundred 
feet  above  the  sea.  In  woods  again,  if  the  loose 
leaves  in  autumn  are  removed,  the  whole  sur- 
face will  be  found  strewed  with  castings.  Dr. 
King,  the  superintendent  of  the  Botanic  Gar- 
den in  Calcutta,  to  whose  kindness  I am  in- 
debted for  many  observations  on  earth-worms, 
informs  me  that  he  found,  near  Nancy  in 
France,  the  bottom  of  the  State  forests  cov- 
ered over  many  acres  with  a spongy  layer, 
composed  of  dead  leaves  and  innumerable 
worm-castings.  He  there  heard  the  Professor 
of  “ Amenagement  des  Forets  ” lecturing  to 
his  pupils,  and  pointing  out  this  case  as  a 
“ beautiful  example  of  the  natural  cultivation 
of  the  soil;  for  year  after  year  the  thrown-up 
castings  cover  the  dead  leaves;  the  result  being 
a rich  humus  of  great  thickness/’ 

* “ Zeitschrift  fur  wissenschaft.  Zoologie,”  B.  xxviii,  1877, 

p.  361- 


6 


INTRODUCTION. 


In  the  year  1869,  Mr.  Fish  * rejected  my 
conclusions  with  respect  to  the  part  which 
worms  have  played  in  the  formation  of  vege- 
table mould,  merely  on  account  of  their  as- 
sumed incapacity  to  do  so  much  work.  He  re- 
marks that  “ considering  their  weakness  and 
their  size,  the  work  they  are  represented  to 
have  accomplished  is  stupendous/’  Here  we 
have  an  instance  of  that  inability  to  sum  up 
the  effects  of  a continually  recurrent  cause, 
which  has  often  retarded  the  progress  of  sci- 
ence, as  formerly  in  the  case  of  geology,  and 
more  recently  in  that  of  the  principle  of  evolu- 
tion. 

Although  these  several  objections  seemed 
to  me  to  have  no  weight,  yet  I resolved  to 
make  more  observations  of  the  same  kind  as 
those  published,  and  to  attack  the  problem  on 
another  side;  namely,  to  weigh  all  the  castings 
thrown  up  within  a given  time  in  a measured 
space,  instead  of  ascertaining  the  rate  at  which 
objects  left  on  the  surface  were  buried  by 
worms.  But  some  of  my  observations  have 
been  rendered  almost  superfluous  by  an  ad- 

* ‘‘Gardeners’  Chronicle,”  April  17,  1869,  p,  418. 


INTRODUCTION. 


7 


mirable  paper  by  Von  Hensen,  already  alluded 
to,  which  appeared  in  1877.  Before  entering 
on  details  with  respect  to  the  castings,  it  will 
be  advisable  to  give  some  account  of  the  habits 
of  worms  from  my  own  observations  and  from 
those  of  other  naturalists. 


CHAPTER  I. 


HABITS  OF  WORMS. 

Nature  of  the  sites  inhabited — Can  live  long  under  water — 
Nocturnal— Wander  about  at  night — Often  lie  close  to  the 
mouths  of  their  burrows,  and  are  thus  destroyed  in  large 
numbers  by  birds — Structure — Do  not  possess  eyes,  but  can 
distinguish  between  light  and  darkness — Retreat  rapidly  when 
brightly  illuminated,  not  by  a reflex  action — Power  of  attention 
— Sensitive  to  heat  and  cold — Completely  deaf — Sensitive  to 
vibrations  and  to  touch — Feeble  power  of  smell — Taste — 
Mental  qualities — Nature  of  food — Omnivorous — Digestion — 
Leaves  before  being  swallowed,  moistened  with  a fluid  of  the 
nature  of  the  pancreatic  secretion — Extra-stomachal  digestion 
— Calciferous  glands,  structure  of — Calcareous  concretions 
formed  in  the  anterior  pair  of  glands — The  calcareous  matter 
primarily  an  excretion,  but  secondarily  serves  to  neutralise  the 
acids  generated  during  the  digestive  process. 

Earth-worms  are  distributed  throughout 
the  world  under  the  form  of  a few  genera, 
which  externally  are  closely  similar  to  one  an- 
other. The  British  species  of  Lumbricus  have 
never  been  carefully  monographed;  but  we 
may  judge  of  their  probable  number  from 
those  inhabiting  neighbouring  countries.  In 

Scandinavia  there  are  eight  species,  according 

8 


Chap.  I. 


SITES  INHABITED. 


9 


to  Eisen;  * but  two  of  these  rarely  burrow  in 
the  ground,  and  one  inhabits  very  wet  places 
or  even  lives  under  the  water.  We  are  here 
concerned  only  with  the  kinds  which  bring 
up  earth  to  the  surface  in  the  form  of  castings. 
Hoffmeister  says  that  the  species  in  Germany 
are  not  well  known,  but  gives  the  same  num- 
ber as  Eisen,  together  with  some  strongly 
marked  varieties.f 

Earth-worms  abound  in  England  in  many 
different  stations.  Their  castings  may  be  seen 
in  extraordinary  numbers  on  commons  and 
chalk-downs,  so  as  almost  to  cover  the  whole 
surface,  where  the  soil  is  poor  and  the  grass 
short  and  thin.  But  they  are  almost  or  quite 
as  numerous  in  some  of  the  London  parks, 
where  the  grass  grows  well  and  the  soil  ap- 
pears rich.  Even  on  the  same  field  worms  are 
much  more  frequent  in  some  places  than  in 
others,  without  any  visible  difference  in  the 
nature  of  the  soil.  They  abound  in  paved 
court-yards  close  to  houses;  and  an  instance 

* “ Bidrag  till  Skandinaviens  Oligochsetfauna,”  1871. 

f “ Die  bis  jetzt  bekannten  Arten  aus  der  Familie  der  Re- 
genwurmer,’,  1845. 


io  HABITS  OF  WORMS.  Chap.  I. 

will  be  given  in  which  they  had  burrowed 
through  the  floor  of  a very  damp  cellar.  I 
have  seen  worms  in  black  peat  in  a boggy 
field;  but  they  are  extremely  rare,  or  quite 
absent  in  the  drier,  brown,  fibrous  peat,  which 
is  so  much  valued  by  gardeners.  On  dry, 
sandy  or  gravelly  tracks,  where  heath  with 
some  gorse,  ferns,  coarse  grass,  moss  and  lich- 
ens alone  grow,  hardly  any  worms  can  be 
found.  But  in  many  parts  of  England,  wher- 
ever a path  crosses  a heath,  its  surface  becomes 
covered  with  a fine  short  sward.  Whether 
this  change  of  vegetation  is  due  to  the  taller 
plants  being  killed  by  the  occasional  trampling 
of  man  and  animals,  or  to  the  soil  being  occa- 
sionally manured  by  the  droppings  from  ani- 
mals, I do  not  know.*  On  such  grassy  paths 
worm-castings  may  often  be  seen.  On  a heath 
in  Surrey,  which  was  carefully  examined,  there 

* There  is  even  some  reason  to  believe  that  pressure  is  actually 
favourable  to  the  growth  of  grasses,  for  Professor  Buckman,  who 
made  many  observations  on  their  growth  in  the  experimental 
gardens  of  the  Royal  Agricultural  College,  remarks  (“  Gardeners’ 
Chronicle,”  1854,  p.  619) : “ Another  circumstance  in  the  culti- 
vation of  grasses  in  the  separate  form  or  small  patches,  is  the 
impossibility  of  rolling  or  treading  them  firmly,  without  which 
no  pasture  can  continue  good.” 


Chap.  I. 


SITES  INHABITED. 


II 


were  only  a few  castings  on  these  paths,  where 
they  were  much  inclined;  but  on  the  more 
level  parts,  where  a bed  of  fine  earth  had  been 
washed  down  from  the  steeper  parts  and  had 
accumulated  to  a thickness  of  a few  inches, 
worm-castings  abounded.  These  spots  seemed 
to  be  overstocked  with  worms,  so  that  they 
had  been  compelled  to  spread  to  a distance  of 
a few  feet  from  the  grassy  paths,  and  here  their 
castings  had  been  thrown  up  among  the  heath; 
but  beyond  this  limit,  not  a single  casting 
could  be  found.  A layer,  though  a thin  one, 
of  fine  earth,  which  probably  long  retains  some 
moisture,  is  in  all  cases,  as  I believe,  necessary1* 
for  their  existence;  and  the  mere  compas- 
sion of  the  soil  appears  to  be  in  some  degree 
favourable  to  them,  for  they  often  abound  in 
old  gravel  walks,  and  in  foot-paths  across 
fields. 

Beneath  large  trees  few  castings  can  be 
found  during  certain  seasons  of  the  year,  and 
this  is  apparently  due  to  the  moisture  having 
been  sucked  out  of  the  ground  by  the  innu- 
merable roots  of  the  trees;  for  such  places  may 
be  seen  covered  with  castings  after  the  heavy 


12 


HABITS  OF  WORMS. 


Chap.  I. 


autumnal  rains.  Although  most  coppices  and 
woods  support  many  worms,  yet  in  a forest  of 
tall  and  ancient  beech-trees  in  Knole  Park, 
where  the  ground  beneath  was  bare  of  all 
vegetation,  not  a single  casting  could  be  found 
over  wide  spaces,  even  during  the  autumn. 
Nevertheless,  castings  were  abundant  on  some 
grass-covered  glades  and  indentations  which 
penetrated  this  forest.  On  the  mountains  of 
North  Wales  and  on  the  Alps,  worms,  as  I 
have  been  informed,  are  in  most  places  rare; 
and  this  may  perhaps  be  due  to  the  close  prox- 
imity of  the  subjacent  rocks,  into  which  worms 
cannot  burrow  during  the  winter  so  as  to  es- 
cape being  frozen.  Dr.  McIntosh,  however, 
found  worm-castings  at  a height  of  1500  feet 
on  Schiehallion  in  Scotland.  They  are  numer- 
ous on  some  hills  near  Turin  at  from  2000  to 
3000  feet  above  the  sea,  and  at  a great  altitude 
on  the  Nilgiri  Mountains  in  South  India  and 
on  the  Himalaya. 

Earth-worms  must  be  considered  as  terres- 
/rial  animals,  though  they  are  still  in  one 
sense  semi-aquatic,  like  the  other  members  of 
the  great  class  of  annelids  to  which  they  be- 


Chap.  I. 


NOCTURNAL. 


13 


long.  M.  Perrier  found  that  their  exposure 
to  the  dry  air  of  a room  for  only  a single  night 
was  fatal  to  them.  On  the  other  hand  he  kept 
several  large  worms  alive  for  nearly  four 
months,  completely  submerged  in  water.* 
During  the  summer  when  the  ground  is  dry, 
they  penetrate  to  a considerable  depth  and 
cease  to  work,  as  they  do  during  the  winter 
when  the  ground  is  frozen.  Worms  are  noc^ 
turnal  in  their  habits,  and  at  night  may  be 
seen  crawling  about  in  large  numbers,  but 
usually  with  their  tails  still  inserted  in  their 
burrows.  By  the  expansion  of  this  part  of 
their  bodies,  and  with  the  help  of  the  short, 
slightly  reflexed  bristles,  with  which  their 
bodies  are  armed,  they  hold  so  fast  that  they 
can  seldom  be  dragged  out  of  the  ground  with- 
out being  torn  into  pieces. f During  the  day 
they  remain  in  their  burrows,  except  at  the 
pairing  season,  when  those  which  inhabit  ad- 

* I shall  have  occasion  often  to  refer  to  M.  Perrier’s  admirable 
memoir,  “ Organisation  des  Lombriciens  terrestres  ” in  “ Ar- 
chives de  Zoolog.  exper.,”  tom.  iii.  1874,  p.  372.  C.  F.  Morren 
(“  De  Lumbrici  terrestris,”  1829,  p.  14)  found  that  worms  en- 
dured immersion  for  fifteen  to  twenty  days  in  summer,  but 
that  in  winter  they  died  when  thus  treated. 

f Morren,  “ De  Lumbrici  terrestris,”  &c.,  1829,  p.  67. 


14 


HABITS  OF  WORMS. 


Chap.  I. 


joining  burrows  expose  the  greater  part  of 
their  bodies  for  an  hour  or  two  in  the  early 
morning.  Sick  individuals,  which  are  gener- 
ally affected  by  the  parasitic  larvae  of  a fly, 
must  also  be  excepted,  as  they  wander  about 
during  the  day  and  die  on  the  surface.  After 
heavy  rain  succeeding  dry  weather,  an  aston- 
ishing number  of  dead  worms  may  sometimes 
be  seen  lying  on  the  ground.  Mr.  Galton  in- 
forms me  that  on  one  such  occasion  (March, 
1881),  the  dead  worms  averaged  one  for  every 
two  and  a half  paces  in  length  on  a walk  in 
Hyde  Park,  four  paces  in  width.  He  counted 
no  less  than  45  dead  worms  in  one  place  in  a 
length  of  sixteen  paces.  From  the  facts  above 
given,  it  is  not  probable  that  these  worms 
could  have  been  drowned,  and  if  they  had  been 
drowned  they  would  have  perished  in  their 
burrows.  I believe  that  they  were  already  sick, 
and  that  their  deaths  were  merely  hastened  by 
the  ground  being  flooded. 

It  has  often  been  said  that  under  ordinary 
circumstances  healthy  worms  never,  or  very 
rarely,  completely  leave  their  burrows  at  night; 
but  this  is  an  error,  as  White  of  Selborne  long 


Chap.  I.  WANDER  FROM  THEIR  BURROWS.  15 

ago  knew.  In  the  morning,  after  there  has 
been  heavy  rain,  the  film  of  mud  or  of  very 
fine  sand  over  gravel-walks  is  often  plainly 
marked  with  their  tracks.  I have  noticed  this 
from  August  to  May,  both  months  included, 
and  it  probably  occurs  during  the  two  remain- 
ing months  of  the  year  when  they  are  wet. 
On  these  occasions,  very  few  dead  worms 
could  anywhere  be  seen.  On  January  31, 
1881,  after  a long-continued  and  unusually 
severe  frost  with  much  snow,  as  soon  as  a 
thaw  set  in,  the  walks  were  marked  with  innu- 
merable tracks.  On  one  occasion,  five  tracks 
were  counted  crossing  a space  of  only  an  inch 
square.  They  could  sometimes  be  traced  either 
to  or  from  the  mouths  of  the  burrows  in  the 
gravel-walks,  for  distances  between  2 or  3 up 
to  15  yards.  I have  never  seen  two  tracks 
leading  to  the  same  burrow;  nor  is  it  likely, 
from  what  we  shall  presently  see  of  their 
sense-organs,  that  a worm  could  find  its  way 
back  to  its  burrow  after  having  once  left  it. 
They  apparently  leave  their  burrows  on  a voy- 
age of  discovery,  and  thus  they  find  new  sites 
to  inhabit. 


i6 


HABITS  OF  WORMS. 


Chap.  I. 


Morren  states  * that  worms  often  lie  for 
hours  almost  motionless  close  beneath  the 
mouths  of  their  burrows.  I have  occasionally 
noticed  the  same  fact  with  worms  kept  in  pots 
in  the  house;  so  that  by  looking  down  into 
their  burrows,  their  heads  could  just  be  seen. 
If  the  ejected  earth  or  rubbish  over  the  bur- 
rows be  suddenly  removed,  the  end  of  the 
worm's  body  may  very  often  be  seen  rapidly 
retreating.  This  habit  of  lying  near  the  sur- 
face leads  to  their  destruction  to  an  immense 
extent.  Every  morning  during  certain  seasons 
of  the  year,  the  thrushes  and  blackbirds  on  all 
the  lawns  throughout  the  country  draw  out 
of  their  holes  an  astonishing  number  of  worms; 
and  this  they  could  not  do,  unless  they  lay 
close  to  the  surface.  It  is  not  probable  that 
worms  behave  in  this  manner  for  the  sake  of 
breathing  fresh  air,  for  we  have  seen  that  they 
can  live  for  a long  time  under  water.  I be- 
lieve that  they  lie  near  the  surface  for  the  sake 
of  warmth,  especially  in  the  morning;  and  we 
shall  hereafter  find  that  they  often  coat  the 
mouths  of  their  burrows  with  leaves,  appar- 

* “ De  Lumbrici  terrestris,”  &c.,  p.  14. 


Chap.  I. 


THEIR  STRUCTURE. 


1 7 


ently  to  prevent  thek  bodies  from  coming  into 
close  contact  with  the  cold  damp  earth.  It  is 
said  that  they  completely  close  their  burrows 
during  the  winter. 

Structure. — A few  remarks  must  be  made 
on  this  subject.  The  body  of  a large  worm 
consists  of  from  ioo  to  200  almost  cylindrical 
rings  or  segments,  each  furnished  with  minute 
bristles.  The  muscular  system  is  well  devel- 
oped. Worms  can  crawl  backwards  as  well 
as  forwards,  and  by  the  aid  of  their  affixed  tails 
can  retreat  with  extraordinary  rapidity  into 
their  burrows.  The  mouth  is  situated  at  the 
anterior  end  of  the  body,  and  is  provided  with 
a little  projection  (lobe  or  lip,  as  it  has  been 
variously  called)  which  is  used  for  prehension. 
Internally,  behind  the  mouth,  there  is  a strong 
pharynx,  shown  in  the  accompanying  dia- 
gram (Fig.  1)  which  is  pushed  forwards  when 
the  animal  eats,  and  this  part  corresponds,  ac- 
cording to  Perrier,  with  the  protrudable  trunk 
or  proboscis  of  other  annelids.  The  pharynx 
leads  into  the  oesophagus,  on  each  side  of 
which  in  the  lower  part  there  are  three  pairs 
of  large  glands,  which  secrete  a surprising 


HABITS  OF  WORMS. 


Chap.  I. 


Mouth. 


Pharynx. 


CEsophagus. 


Calciferous 

glands. 


(Esophagus. 


Crop. 


Gizzard. 


Upper  part 
of  intestine. 

Fig.  i.  — Diagram 
of  the  alimentary 
canal  of  an  earth- 
worm (Lumbri- 
cus),  copied  from 
Ray  Lankesterin 
“ Quart.  Jour,  of 
Microscop.  Soc.” 
vol.  xv.  N.S.  pi. 
vii. 


amount  of  carbonate  of  lime. 
These  calciferol^  glands  are 
highly  remarkable,  for  nothing 
like  them  is  known  in  any  other 
animal.  Their  use  will  be  dis- 
cussed when  we  treat  of  the  di- 
gestive process.  In  most  of 
the  species,  the  oesophagus  is 
enlarged  into  a crop  in  front  of 
the  gizzard.  This  latter  organ 
is  lined  with  a smooth  thick 
chitinous  membrane,  and  is 
surrounded  by  weak  longitu- 
dinal, but  by  powerful  trans- 
verse muscles.  Perrier  saw 
these  muscles  in  energetic  ac- 
tion; and,  as  he  remarks,  the 
trituration  of  the  food  must  be 
chiefly  effected  by  this  organ, 
for  worms  possess  no  jaws  or 
teeth  of  any  kind.  Grains  of 
sand  and  small  stones,  from  the 
to  a little  more  than  the  Tff 
inch  in  diameter,  may  generally 
be  found  in  their  gizzards  and 


Chap.  I. 


THEIR  SENSES. 


19 

intestines.  As  it  is  certain  that  worms  swallow 
many  little  stones,  independently  of  those  swal- 
lowed while  excavating  their  burrows,  it  is 
probable  that  they  serve,  like  mill-stones,  to 
triturate  their  food.  The  gizzard  opens  into 
the  intestine,  which  runs  in  a straight  course 
to  the  vent  at  the  posterior  end  of  the  body. 
The  intestine  presents  a remarkable  structure, 
the  typhosol^s,  or,  as  the  old  anatomists  called 
it,  an  intestine  within  an  intestine;  and  Clapa- 
rede  * has  shown  that  this  consists  of  a deep 
longitudinal  involution  of  the  walls  of  the  in- 
testine, by  which  means  an  extensive  absorb- 
ent surface  is  gained. 

The  circulatory  system  is  well  developed. 
Worms  breathe  by  their  skin,  as  they  do  not 
possess  any  special  respiratory  organs.  The 
two  sexes  are  united  in  the  same  individual,  but 
two  individuals  pair  together.  The  nervous 
system  is  fairly  well  developed;  and  the  two 
almost  confluent  cerebral  ganglia  are  situated 
very  near  to  the  anterior  end  of  the  body. 

Senses. — Worms  are  destitute  of  eyes,  and 

* Histolog.  Untersuchungen  liber  die  Regenwiirmer.  “ Zeit- 
schrift  fur  wissenschaft.  Zoologie,”  B.  xix.,  1869,  p.  61 1. 


20 


HABITS  OF  WORMS. 


Chap.  I. 


at  first  I thought  that  they  were  quite  insensi- 
ble to  light;  for  those  kept  in  confinement 
were  repeatedly  observed  by  the  aid  of  a can- 
dle, and  others  out  of  doors  by  the  aid  of  a lan- 
tern, yet  they  were  rarely  alarmed,  although 
extremely  timid  animals.  Other  persons  have 
found  no  difficulty  in  observing  worms  at  night 
by  the  same  means.* 

Hoffmeister,  however,  states  f that  worms, 
with  the  exception  of  a few  individuals,  are 
extremely  sensitive  to  light;  but  he  admits 
that  in  most  cases  a certain  time  is  requisite 
for  its  action.  These  statements  led  me  to 
watch  on  many  successive  nights  worms  kept 
in  pots,  which  were  protected  from  currents 
of  air  by  means  of  glass  plates.  The  pots  were 
approached  very  gently,  in  order  that  no  vi- 
bration of  the  floor  should  be  caused.  When 
under  these  circumstances  worms  were  illu- 
minated by  a bull’s-eye  lantern  having  slides 
of  dark  red  and  blue  glass,  which  intercepted 
so  much  light  that  they  could  be  seen  only 

* For  instance,  Mr.  Bridgman  and  Mr.  Newman  (“The 
Zoologist,”  vol.  vii.  1849,  p.  2576),  and  some  friends  who  ob- 
served worms  for  me. 

f “Familie  der  Regenwiirmer,”  1845,  p.  18. 


Chap.  I. 


THEIR  SENSES. 


21 


with  some  difficulty,  they  were  not  at  all  af- 
fected by  this  amount  of  light,  however  long 
they  were  exposed  to  it.  The  light,  as  far  as 
I could  judge^  was  brighter  than  that  from 
the  full  moon.  Its  colour  apparently  made 
no  difference  in  the  result.  When  they  were 
illuminated  by  a candle,  or  even  by  a bright 
paraffin  lamp,  they  were  not  usually  affected 
at  first.  Nor  were  they  when  the  light  was 
alternately  admitted  and  shut  off.  Sometimes, 
however,  they  behaved  very  differently,  for  as 
soon  as  the  light  fell  on  them,  they  withdrew 
into  their  burrows  with  almost  instantaneous 
rapidity.  This  occurred  perhaps  once  out  of 
a dozen  times.  When  they  did  not  withdraw 
instantly,  they  often  raised  the  anterior  taper- 
ing ends  of  their  bodies  from  the  ground,  as  if 
their  attention  was  aroused  or  as  if  surprise 
was  felt;  or  they  moved  their  bodies  from  side 


appeared  distressed  by  the  light;  but  I doubt 
whether  this  was  really  the  case,  for  on  two 
occasions  after  withdrawing  slowly,  they  re- 
mained for  a long  time  with  their  anterior  ex- 
tremities protruding  a little  from  the  mouths 


to  side  as  if  feeling  for  some  object. 


22 


HABITS  OF  WORMS. 


Chap.  I. 


of  their  burrows,  in  which  position  they  were 
ready  for  instant  and  complete  withdrawal. 

When  the  light  from  a candle  was  concen- 
trated by  means  of  a large  lens  on  the  anterior 
extremity,  they  generally  withdrew  instantly; 
but  this  concentrated  light  failed  to  act  per- 
haps once  out  of  half  a dozen  trials.  The  light 
was  on  one  occasion  concentrated  on  a worm 
lying  beneath  water  in  a saucer,  and  it  instant- 
ly withdrew  into  its  burrow.  In  all  cases  the 
duration  of  the  light,  unless  extremely  feeble, 
made  a great  difference  in  the  result;  for 
worms  left  exposed  before  a paraffin  lamp  or  a 
candle  invariably  retreated  into  their  burrows 
within  from  five  to  fifteen  minutes;  and  if  in 
the  evening  the  pots  were  illuminated  before 
the  worms  had  come  out  of  their  burrows,  they 
failed  to  appear. 

H^Jom  the  foregoing  facts  it  is  evident  that 
light  affects  worms  by  its  intensity  and  by 
its  duration.  It  is  only  the  anterior  ex- 
tremity of  the  body,  where  the  cerebral  gan- 
glia lie,  which  is  affected  by  light,  as  Hoff- 
meister  asserts,  and  as  I observed  on  many 
occasions.  If  this  part  is  shaded,  other 


Chap.  I. 


THEIR  SENSES. 


23 


parts  of  the  body  may  be  fully  illuminated, 
and  no  effect  will  be  produced.  As  these 
animals  have  no  eyes,  we  must  suppose  that 
the  light  passes  through  their  skins,  and  in 
some  manner  excites  their  cerebral  ganglia. 
It  appeared  at  first  probable  that  the  dif- 
ferent manner  in  which  they  were  affected  on 
different  occasions  might  be  explained,  either 
by  the  degree  of  extension  of  their  skin  and 
its  consequent  transparency,  or  by  some  par- 
ticular incidence  of  the  light;  but  I could  dis- 
cover no  such  relation.  One  thing  was  mani- 
fest, namely  that  when  worms  were  employed 
in  dragging  leaves  into  their  burrows  or  in 
eating  them,  and  even  during  the  short  inter- 
vals whilst  they  rested  from  their  work,  they 
either  did  not  perceive  the  light  or  were  re- 
gardless of  it;  and  this  occurred  even  when 
the  light  was  concentrated  on  them  through 
a large  lens.  So,  again,  whilst  they  are  paired, 
they  will  remain  for  an  hour  or  two  out  of 
their  burrows,  fully'  exposed  to  the  morning 
light;  but  it  appears  from  what  Hoffmeister 
says  that  a light  will  occasionally  cause  paired 
individuals  to  separate. 


24 


HABITS  OF  WORMS. 


Chap.  I. 


When  a worm  is  suddenly  illuminated  and 
dashes  like  a rabbit  into  its  burrow — to  use 
the  expression  employed  by  a friend — we  are 
at  first  led  to  look  at  the  action  as  a reflex  one. 
The  irritation  of  the  cerebral  ganglia  appears 
to  cause  certain  muscles  to  contract  in  an 
inevitable  manner,  independently  of  the  will 
or  consciousness  of  the  animal,  as  if  it  were 
an  automaton.  But  the  different  effect  which 
a light  produced  on  different  occasions,  and 
especially  the  fact  that  a worm  when  in  any 
way  employed  and  in  the  intervals  of  such  em- 
ployment, whatever  set  of  muscles  and  gan- 
glia may  then  have  been  brought  into  play,  is 
often  regardless  of  light,  are  opposed  to  the 
view  of  the  sudden  withdrawal  being  a sim- 
ple reflex  action.  With  the  higher  animals, 
when  close  attention  to  some  object  leads  to 
the  disregard  of  the  impressions  which  other 
objects  must  be  producing  on  them,  we  at- 
tribute this  to  their  attention  being  then  ab- 
sorbed; and  attention  implies  the  presence  of 
a mind.  Every  sportsman  knows  that  he  can 
approach  animals  whilst  they  are  grazing, 
fighting  or  courting,  much  more  easily  than 


Chap.  I.  THEIR  SENSES.  25 

at  other  times.  The  state,  also,  of  the  nervous 
system  of*  the  higher  animals  differs  much  at 
different  times,  for  instance,  a horse  is  much 
more  readily  startled  at  one  time  than  at  an- 
other. The  comparison  here  implied  between 
the  actions  of  one  of  the  higher  animals  and 
of  one  so  low  in  the  scale  as  an  earth-worm, 
may  appear  far-fetched;  for  we  thus  attribute 
to  the  worm  attention  and  some  mental  power, 
nevertheless  I can  see  no  reason  to  doubt  the 
justice  of  the  comparison. 

Although  worms  cannot  be  said  to  possess 
the  power  of  vision,  their  sensitiveness  to  light 
enables  them  to  distinguish  between  day  and 
night;  and  they  thus  escape  extreme  danger 
from  the  many  diurnal  animals  which  prey  on 
them.  Their  withdrawal  into  their  burrows 
during  the  day  appears,  however,  to  have  be- 
come an  habitual  action;  for  worms  kept  in 
pots  covered  by  glass-plates,  over  which  sheets 
of  black  paper  were  spread,  and  placed  before 
a north-east  window,  remained  during  the  day- 
time in  their  burrows  and  came  out  every 
night;  and  they  continued  thus  to  act  for  a 

week.  No  doubt  a little  light  may  have  en- 
3 


2 6 


HABITS  OF  WORMS. 


Chap.  I. 


terecl  between  the  sheets  of  glass  and  the  black- 
ened paper;  but  we  know  from  the  trials  with 
coloured  glass,  that  worms  are  indifferent  to 
a small  amount  of  light. 

Worms  appear  to  be  less  sensitive  jo  mod- 
erate radiant  heat  than  to  a bright  light.  I 
judge  of  this  from  having  held  at  different 
times  a poker  heated  to  dull  redness  near  some 
worms,  at  a distance  which  caused  a very  sen- 
sible degree  of  warmth  in  my  hand.  One  of 
them  took  no  notice;  a second  withdrew  into 
its  burrow,  but  not  quickly;  the  third  and 
fourth  much  more  quickly,  and  the  fifth  as 
quickly  as  possible.  The  light  from  a candle, 
concentrated  by  a lens  and  passing  through 
a sheet  of  glass  which  would  intercept  most  of 
the  heat-rays,  generally  caused  a much  more 
rapid  retreat  than  did  the  heated  poker. 
Worms  are  sensitive  to  a low  temperature,  as 
may  be  inferred  from  their  not  coming  out  of 
their  burrows  during  a frost.  I 

Worms  do  not  possess  any  sense  of  War- 
ing. They  took  not  the  least  notice  of  the 
shrill  notes  from  a metal  whistle,  which  was  re- 
peatedly sounded  near  them;  nor  did  they  of 


Chap.  I. 


THEIR  SENSES. 


27 


the  deepest  and  loudest  tones  of  a bassoon. 
They  were  indifferent  to  shouts,  if  care  was 
taken  that  the  breath  did  not  strike  them. 
When  placed  on  a table  close  to  the  keys  of 
a piano,  which  was  played  as  loudly  as  pos- 
sible, they  remained  perfectly  quiet. 

Although  they  are  indifferent  to  undula- 
tions in  the  air  audible  by  us,  they  are  ex- 
tremely sensitive  to  vibratioffs  in  any  solid 
object.  When  the  pots  containing  two  worms 
which  had  remained  quite  indifferent  to  the 
sound  of  the  piano,  were  placed  on  this  instru- 
ment, and  the  note  C in  the  bass  clef  was 
struck,  both  instantly  retreated  into  their  bur- 
rows. After  a time  they  emerged,  and  when 
G above  the  line  in  the  treble  clef  was  struck 
they  again  retreated.  Under  similar  circum- 
stances on  another  night  one  worm  dashed 
into  its  burrow  on  a very  high  note  being 
struck  only  once,  and  the  other  worm  when 
C in  the  treble  clef  was  struck.  On  these  oc- 
casions the  worms  were  not  touching  the  sides 
of  the  pots,  which  stood  in  saucers;  so  that 
the  vibrations,  before  reaching  their  bodies, 
had  to  pass  from  the  sounding  board  of  the 


28 


HABITS  OF  WORMS. 


Chap.  I. 


piano,  through  the  saucer,  the  bottom  of  the 
pot  and  the  damp,  not  very  compact  earth  on 
which  they  lay  with  their  tails  in  their  burrows. 
They  often  showed  their  sensitiveness  when 
the  pot  in  which  they  lived,  or  the  table  on 
which  the  pot  stood,  was  accidentally  and 
lightly  struck;  but  they  appeared  less  sensi- 
tive to  such  jars  than  to  the  vibrations  of  the 
piano;  and  their  sensitiveness  to  jars  varied 
much  at  different  times.  It  has  often  been 
said  that  if  the  ground  is  beaten  or  otherwise 
made  to  tremble,  worms  believe  that  they  are 
pursued  by  a mole  and  leave  their  burrows. 
I beat  the  ground  in  many  places  where  worms 
abounded,  but  not  one  emerged.  When,  how- 
ever, the  ground  is  dug  with  a fork  and  is  vio- 
lently disturbed  beneath  a worm,  it  will  often 
crawl  quickly  out  of  its  burrow. 

The  whole  body  of  a worm  is  sensitive  to 
contact.  A slight  puff  of  air  from  the  mouth 
causes  an  instant  retreat.  The  glass  plates 
placed  over  the  pots  did  not  fit  closely,  and 
blowing  through  the  very  narrow  chinks  thus 
left,  often  sufficed  to  cause  a rapid  retreat. 
They  sometimes  perceived  the  eddies  in  the 


Chap.  I. 


THEIR  SENSES. 


29 


air  caused  by  quickly  removing  the  glass 
plates.  When  a worm  first  comes  out  of  its 
burrow,  it  generally  moves  the  much  extended 
anterior  extremity  of  its  body  from  side  to 
side  in  all  directions,  apparently  as  an  organ 
of  touch;  and  there  is  some  reason  to  believe, 
as  we  shall  see  in  the  next  chapter,  that  they 
are  thus  enabled  to  gain  a general  notion  of  the 
form  of  an  object.  Of  all  their  senses  that  of 
touch,  including  in  this  term  the  perception 
of  a vibration,  seems  much  the  most  highly  de- 
veloped. 

In  worms  the  sense  of  smell  apparently  is 
confined  to  the  perception  orcertain  odours, 
and  is  feeble.  They  were  quite  indifferent  to 
my  breath,  as  long  as  I breathed  on  them  very 
gently.  This  was  tried,  because  it  appeared 
possible  that  they  might  thus  be  warned  of 
the  approach  of  an  enemy.  They  exhibited 
the  same  indifference  to  my  breath  whilst  I 
chewed  some  tobacco,  and  while  a pellet  of 
cotton-wool  with  a few  drops  of  mille-fleurs 
perfume  or  of  acetic  acid  was  kept  in  my 
mouth.  Pellets  of  cotton-woo?  soaked  in  to- 
bacco juice,  and  in  mille-fleurs  perfume,  and 


30 


HABITS  OF  WORMS. 


Chap.  I. 


in  paraffin,  were  held  with  pincers  and  were 
waved  about  within  two  or  three  inches  of 
several  worms,  but  they  took  no  notice.  On 
one  or  two  occasions,  however,  when  acetic 
acid  had  been  placed  on  the  pellets,  the  worms 
appeared  a little  uneasy,  and  this  was  prob- 
ably due  to  the  irritation  of  their  skins.  The 
perception  of  such  unnatural  odours  would 
be  of  no  service  to  worms;  and  as  such  timid 
creatures  would  almost  certainly  exhibit  some 
signs  of  any  new  impression,  we  may  conclude 
that  they  did  not  perceive  these  odours. 

The  result  was  different  when  cabbage- 
leaves  and  pieces  of  onion  were  employed, 
both  of  which  are  devoured  with  much  relish 
by  worms.  Small  square  pieces  of  fresh  and 
half-decayed  cabbage-leaves  and  of  onion 
bulbs  were  on  nine  occasions  buried  in  my 
pots,  beneath  about  \ of  an  inch  of  common 
garden  soil;  and  they  were  always  discovered 
by  the  worms.  One  bit  of  cabbage  was  dis- 
covered and  removed  in  the  course  of  two 
hours;  three  were  removed  by  the  next  morn- 
ing, that  is,  after  a single  night;  two  others 
after  two  nights;  and  the  seventh  bit  after 


Chap.  I. 


THEIR  SENSES. 


31 


three  nights*  Two  pieces  of  onion  were  dis- 
covered and  removed  after  three  nights.  Bits 
of  fresh  raw  meat,  of  which  worms  are  very 
fond,  were  buried,  and  were  not  discovered 
within  forty-eight  hours,  during  which  time 
they  had  not  become  putrid.  The  earth  above 
the  various  buried  objects  was  generally 
pressed  down  only  slightly,  so  as  not  to  pre- 
vent the  emission  of  any  odour.  On  two  oc- 
casions, however,  the  surface  was  well  watered, 
and  was  thus  rendered  somewhat  compact. 
After  the  bits  of  cabbage  and  onion  had  been 
removed,  I looked  beneath  them  to  see  wheth- 
er the  worms  had  accidentally  come  up  from 
below,  but  there  was  no  sign  of  a burrow; 
and  twice  the  buried  objects  were  laid  on 
pieces  of  tin-foil  which  were  not  in  the  least 
displaced.  It  is  of  course  possible  that  the 
worms  whilst  moving  about  on  the  surface  of 
the  ground,  with  their  tails  affixed  within  their 
burrows,  may  have  poked  their  heads  into  the 
places  where  the  above  objects  were  buried; 
but  I have  never  seen  worms  acting  in  this 
manner.  Some  pieces  of  cabbage-leaf  and  of 
onion  were  twice  buried  beneath  very  fine  fer- 


32 


HABITS  OF  WORMS. 


Chap.  I. 


ruginous  sand,  which  was  slightly  pressed 
down  and  well  watered,  so  as  to  be  rendered 
very  compact,  and  these  pieces  were  never  dis- 
covered. On  a third  occasion  the  same  kind 
of  sand  was  neither  pressed  down  nor  watered, 
and  the  pieces  of  cabbage  were  discovered  and 
removed  after  the  second  night.  These  several 
facts  indicate  that  worms  possess  some  power 
of  smell;  and  that  they  discover  by  this  means 
odoriferous  and  much-coveted  kinds  of  food. 

It  may  be  presumed  that  all  animals  which 
feed  on  various  substances  posse<^  the  sense 
of  taste,  and  this  is  certainly  the  case  with 
worms.  Cabbage-leaves  are  much  liked  by 
worms;  and  it  appears  that  they  can  distin- 
guish between  different  varieties;  but  this  may 
perhaps  be  owing  to  differences  in  their  tex- 
ture. On  eleven  occasions  pieces  of  the  fresh 
leaves  of  a common  green  variety  and  of  the 
red  variety  used  for  pickling  were  given  them, 
and  they  preferred  the  green,  the  red  being 
either  wholly  neglected  or  much  less  gnawed. 
On  two  other  occasions,  however,  they  seemed 
to  prefer  the  red.  Half-decayed  leaves  of  the 
red  variety  and  fresh  leaves  of  the  green  were 


Chap.  I. 


THEIR  SENSES. 


33 


attacked  about  equally.  When  leaves  of  the 
cabbage,  horse-radish  (a  favourite  food)  and 
of  the  onion  were  given  together,  the  latter 
were  always  and  manifestly  preferred.  Leaves 
of  the  cabbage,  lime-tree,  Ampelopis,  parsnip 
(Pastinaca),  and  celery  (Apium)  were  likewise 
given  together;  and  those  of  the  celery  were 
first  eaten.  But  when  leaves  of  cabbage, 
turnip,  beet,  celery,  wild  cherry  and  carrots 
were  given  together,  the  two  latter  kinds,  espe- 
cially those  of  the  carrot,  were  preferred  to  all 
the  others,  including  those  of  celery.  It  was 
also  manifest  after  many  trials  that  wild  cherry 
leaves  were  greatly  preferred  to  those  of  the 
lime-tree  and  hazel  (Corylus).  According  to 
Mr.  Bridgman  the  half-decayed  leaves  of  Phlox 
verna  are  particularly  liked  by  worms.* 

Pieces  of  the  leaves  of  cabbage,  turnip, 
horse-radish  and  onion  were  left  on  the  pots 
during  22  days,  and  were  all  attacked  and  had 
to  be  renewed;  but  during  the  whole  of  this 
time  leaves  of  an  Artemisia  and  of  the  culinary 
sage,  thyme  and  mint,  mingled  with  the  above 
leaves,  were  quite  neglected  excepting  those 

* “ The  Zoologist,”  vol.  vii.  1849,  p.  2576. 


34 


HABITS  OF  WORMS. 


Chap.  I. 


of  the  mint,  which  were  occasionally  and  very 
slightly  nibbled.  These  latter  four  kinds  of 
leaves  do  not  differ  in  texture  in  a manner 
which  could  make  them  disagreeable  to 
worms;  they  all  have  a strong  taste,  but  so 
have  the  four  first  mentioned  kinds  of  leaves; 
and  the  wide  difference  in  the  result  must  be 
attributed  to  a preference  by  the  worms  for 
one  taste  over  another. 

Mental  Qualities. — There  is  little  to  be  said 
on  this  head.  We  have  seen  that  worms  are 
timid.  It  may  be  doubted  whether  they  suffer 
as  much  pain  when  injured,  as  they  seem  to 
express  by  their  contortions.  Judging  by  their 
eagerness  for  certain  kinds  of  food,  they  must 
enjoy  the  pleasure  of  eating.  Their  sexual 
passion  is  strong  enough  to  overcome  for  a 
time  their  dread  of  light.  They  perhaps  have 
a trace  of  social  feeling,  for  they  are  not  dis- 
turbed by  crawling  over  each  other’s  bodies, 
and  they  sometimes  lie  in  contact.  According 
to  Hoffmeister  they  pass  the  winter  either  sin- 
gly or  rolled  up  with  others  into  a ball  at  the 
bottom  of  their  burrows.*  Although  worms 

* “Familie  der  Regenwiirmer,”  p.  13. 


Chap.  I. 


MENTAL  QUALITIES. 


35 


are  so  remarkably  deficient  in  the  several  sense- 
organs,  this  does  not  necessarily  preclude  in- 
telligence, as  we  know  from  such  cases  as  those 
of  Laura  Bridgman;  and  we  have  seen  that 
when  their  attention  is  engaged,  they  neglect 
impression  to  which  they  would  otherwise 
have  attended;  and  attention  indicates  the 
presence  of  a mind  of  some  kind.  They  are 
also  much  more  easily  excited  at  certain  times 
than  at  others.  They  perform  a few  actions 
instinctively,  that  is,  all  the  individuals,  includ- 
ing the  young,  perform  such  actions  in  nearly 
the  same  fashion.  This  is  shown  by  the  man- 
ner in  which  the  species  of  Perichaeta  eject 
their  castings,  so  as  to  construct  towers;  also 
by  the  manner  in  which  the  burrows  of  the 
common  earth-worm  are  smoothly  lined  with 
fine  earth  and  often  with  little  stones,  and  the 
mouths  of  their  burrows  with  leaves.  One  of 
their  strongest  instincts  is  the  plugging  up  the 
mouths  of  their  burrows  with  various  objects; 
and  very  young  worms  act  in  this  manner. 
But  some  degree  of  intelligence  appears,  as  we 
shall  see  in  the  next  chapter,  to  be  exhibited 
in  this  work, — a result  which  has  surprised 


36  HABITS  OF  WORMS.  Chap.  I. 

me  more  than  anything  else  in  regard  to 
worms. 

Food  and  Digestion. — Worms  are  omnivo- 
rous. They  swallow  an  enormous  quantity  of 
earth,  out  of  which  they  extract  any  digesti- 
ble matter  which  it  may  contain;  but  to  this 
subject  I must  recur.  They  also  consume  a 
large  number  of  half-decayed  leaves  of  all 
kinds,  excepting  a few  which  have  an  unpleas- 
ant taste  or  are  too  tough  for  them;  likewise 
petioles,  peduncles  and  decayed  flowers.  But 
they  will  also  consume  fresh  leaves,  as  I have 
found  by  repeated  trials.  According  to  Mor- 
ren  * they  will  eat  particles  of  sugar  and  liquor- 
ice; and  the  worms  which  I kept  drew  many 
bits  of  dry  starch  into  their  burrows,  and  a 
large  bit  had  its  angles  well  rounded  by  the 
fluid  poured  out  of  their  mouths.  But  as  they 
often  drag  particles  of  soft  stone,  such  as  of 
chalk,  into  their  burrows,  I feel  some  doubt 
whether  the  starch  was  used  as  food.  Pieces 
of  raw  and  roasted  meat  were  fixed  several 
times  by  long  pins  to  the  surface  of  the  soil  in 
my  pots,  and  night  after  night  the  worms 

* “ De  Lumbrici  terrestris p.  19. 


Chap.  I. 


FOOD  AND  DIGESTION. 


37 


could  be  seen  tugging  at  them,  with  the  edges 
of  the  pieces  engulfed  in  their  mouths,  so  that 
much  was  consumed.  Raw  fat  seems  to  be 
preferred  even  to  raw  meat  or  to  any  other 
substance  which  was  given  them,  and  much 
was  consumed.  They  are  cannibals,  for  the 
two  halves  of  a dead  worm  placed  in  two  of 
the  pots  were  dragged  into  the  burrows  and 
gnawed;  but  as  far  as  I could  judge,  they  pre- 
fer fresh  to  putrid  meat,  and  in  so  far  I differ 
from  Hoffmeister. 

Leon  Fredericq  states  * that  the  digestive 
fluid  of  worms  is  of  the  same  nature  as  the 
pancreatic  secretion  of  the  higher  animals; 
and  this  conclusion  agrees  perfectly  with  the 
kinds  of  food  which  worms  consume.  Pan- 
creatic juice  emulsifies  fat,  and  we  have  just 
seen  how  greedily  worms  devour  fat;  it  dis- 
solves fibrin,  and  worms  eat  raw  meat;  it  con- 
verts starch  into  grape-sugar  with  wonderful 
rapidity,  and  we  shall  presently  show  that  the 
digestive  fluid  of  worms  acts  on  starch. f But 

* “ Archives  de  Zoologie  experimentale,”  tom.  vii,  1878, 
P*  394. 

f On  the  action  of  the  pancreatic  ferment,  see  “ A Text-Book 
of  Physiology,”  by  Michael  Foster,  2nd  edit.  pp.  198-203.  1878. 


78  / HABITS  OF  WORMS.  Chap.  I. 

/ 

the>k/live  chiefly  on  half-decayed  leaves;  and 
these  would  be  useless  to  them  unless  they 
could  digest  the  cellulose  forming  the  cell- 
walls;  for  it  is  well  known  that  all  other  nutri- 
tious substances  are  almost  completely  with- 
drawn from  leaves,  shortly  before  they  fall  off. 
It  has,  however,  now  been  ascertained  that 
cellulose,  though  very  little  or  not  at  all  at- 
tacked by  the  gastric  secretion  of  the  higher 
animals,  is  acted  on  by  that  from  the  pan- 
creas.* 

The  half-decayed  or  fresh  leaves  which 
worms  intend  to  devour,  are  dragged  into  the 
mouths  of  their  burrows  to  a depth  of  from 
one  to  three  inches,  and  are  then  moistened 
with  a secreted  fluid.  It  has  been  assumed 
that  this  fluid  serves  to  hasten  their  decay;  but 
a large  number  of  leaves  were  twice  pulled 
out  of  the  burrows  of  worms  and  kept  for 
many  weeks  in  a very  moist  atmosphere  under 
a bell-glass  in  my  study;  and  the  parts  which 
had  been  moistened  by  the  worms  did  not  de- 
cay more  quickly  in  any  plain  manner  than  the 

* Schmulewitsch,  Action  des  Sues  digestifs  sur  la  Cellulose. 
“ Bull,  de  l’Acad.  Imp.  de  St.  Petersbourg,”  tom.  xxv.  p.  549. 
1879. 


Chap.  I. 


FOOD  AND  DIGESTION. 


39 


other  parts.  When  fresh  leaves  were  given  in 
the  evening  to  worms  kept  in  confinement  and 
examined  early  on  the  next  morning,  therefore 
not  many  hours  after  they  had  been  dragged 
into  the  burrows,  the  fluid  with  which  they 
were  moistened,  when  tested  with  neutral 
litmus  paper,  showed  an  alkaline  reaction. 
This  was  repeatedly  found  to  be  the  case  with 
celery,  cabbage  and  turnip  leaves.  Parts  of 
the  same  leaves  which  had  not  been  moistened 
by  the  worms,  were  pounded  with  a few  drops 
of  distilled  water,  and  the  juice  thus  extracted 
was  not  alkaline.  Some  leaves,  however, 
which  had  been  drawn  into  burrows  out  of 
doors,  at  an  unknown  antecedent  period,  were 
tried,  and  though  still  moist,  they  rarely  ex- 
hibited even  a trace  of  alkaline  reaction. 

The  fluid,  with  which  the  leaves  are  bathed, 
acts  on  them  whilst  they  are  fresh  or  nearly 
fresh,  in  a remarkable  manner;  for  it  quickly 
kills  and  discolours  them.  Thus  the  ends  of 
a fresh  carrot-leaf,  which  had  been  dragged 
into  a burrow,  were  found  after  twelve  hours 
of  a dark  brown  tint.  Leaves  of  celery,  turnip, 
maple,  elm,  lime,  thin  leaves  of  ivy,  and  oc- 


40 


HABITS  OF  WORMS. 


Chap.  I. 


casionally  those  of  the  cabbage  were  similarly 
acted  on.  The  end  of  a leaf  of  Triticum  repens, 
still  attached  to  a growing  plant,  had  been 
drawn  into  a burrow,  and  this  part  was  dark 
brown  and  dead,  whilst  the  rest  of  the  leaf 
was  fresh  and  green.  Several  leaves  of  lime 
and  elm  removed  from  burrows  out  of  doors 
were  found  affected  in  different  degrees.  The 
first  change  appears  to  be  that  the  veins  be- 
come of  a dull  reddish-orange.  The  cells  with 
chlorophyll  next  lose  more  or  less  completely 
their  green  colour,  and  their  contents  finally 
become  brown.  The  parts  thus  affected  often 
appeared  almost  black  by  reflected  light;  but 
when  viewed  as  a transparent  object  under  the 
microscope,  minute  specks  of  light  were  trans- 
mitted, and  this  was  not  the  case  with  the  un- 
affected parts  of  the  same  leaves.  These  ef- 
fects, however,  merely  show  that  the  secreted 
fluid  is  highly  injurious  or  poisonous  to  leaves; 
for  nearly  the  same  effects  were  produced  in 
from  one  to  two  days  on  various  kinds  of 
young  leaves,  not  only  by  artificial  pancreatic 
fluid,  prepared  with  or  without  thymol,  but 
quickly  by  a solution  of  thymol  by  itself.  On 


Chap.  I. 


FOOD  AND  DIGESTION. 


41 


one  occasion  leaves  of  Corylus  were  much  dis- 
coloured by  being  kept  for  eighteen  hours  in 
pancreatic  fluid,  without  any  thymol.  With 
young  and  tender  leaves  immersion  in  human 
saliva  during  rather  warm  weather,  acted  in 
the  same  manner  as  the  pancreatic  fluid,  but 
not  so  quickly.  The  leaves  in  all  these  cases 
often  became  infiltrated  with  the  fluid. 

Large  leaves  from  an  ivy  plant  growing 
on  a wall  were  so  tough  that  they  could  not 
be  gnawed  by  worms,  but  after  four  days  they 
were  affected  in  a peculiar  manner  by  the  se- 
cretion poured  out  of  their  mouths.  The 
upper  surfaces  of  the  leaves,  over  which  the 
worms  had  crawled,  as  was  shown  by  the  dirt 
left  on  them,  were  marked  in  sinuous  lines, 
by  either  a continuous  or  broken  chain  of 
whitish  and  often  star-shaped  dots,  about  2 
mm.  in  diameter.  The  appearance  thus  pre- 
sented was  curiously  like  that  of  a leaf,  into 
which  the  larva  of  some  minute  insect  had 
burrowed.  But  my  son  Francis,  after  making 
and  examining  sections,  could  nowhere  find 
that  the  cell-walls  had  been  broken  down  or 
that  the  epidermis  had  been  penetrated. 


42 


HABITS  OF  WORMS. 


Chap.  I. 


When  the  section  passed  through  the  whitish 
dots,  the  grains  of  chlorophyll  were  seen  to 
be  more  or  less  discoloured,  and  some  of  the 
palisade  and  mesophyll  cells  contained  noth- 
ing but  broken  down  granular  matter.  These 
effects  must  be  attributed  to  the  transudation 
of  the  secretion  through  the  epidermis  into  the 
cells. 

The  secretion  with  which  worms  moisten 
leaves  likewise  acts  on  the  starch  granules 
within  the  cells.  My  son  examined  some 
leaves  of  the  ash  and  many  of  the  lime,  which 
had  fallen  off  the  trees  and  had  been  partly 
dragged  into  worm-burrows.  It  is  known  that 
with  fallen  leaves  the  starch-grains  are  pre- 
served in  the  guard-cells  of  the  stomata.  Now 
in  several  cases  the  starch  had  partially  or 
wholly  disappeared  from  these  cells,  in  the 
parts  which  had  been  moistened  by  the  secre- 
tion; while  they  were  still  well  preserved  in  the 
other  parts  of  the  same  leaves.  Sometimes 
the  starch  was  dissolved  out  of  only  one  of  the 
two  guard-cells.  The  nucleus  in  one  case  had 
disappeared,  together  with  the  starch-granules. 
The  mere  burying  of  lime-leaves  in  damp  earth 


Chap.  I. 


FOOD  AND  DIGESTION. 


43 


for  nine  days  did  not  cause  the  destruction  of 
the  starch-granules.  On  the  other  hand,  the 
immersion  of  fresh  lime  and  cherry  leaves  for 
eighteen  hours  in  artificial  pancreatic  fluid,  led 
to  the  dissolution  of  the  starch-granules  in  the 
guard-cells  as  well  as  in  the  other  cells. 

From  the  secretion  with  which  the  leaves 
are  moistened  being  alkaline,  and  from  its 
acting  both  on  the  starch-granules  and  on  the 
protoplasmic  contents  of  the  cells,  we  may 
infer  that  it  resembles  in  nature  not  saliva,* 
but  pancreatic  secretion;  and  we  know  from 
Fredericq  that  a secretion  of  this  kind  is  found 

in  the  intestines  of  worms.  As  the  leaves 

V 

which  are  dragged  into  the  burrows  are  often 
dry  and  shrivelled,  it  is  indispensable  for  their 
disintegration  by  the  unarmed  mouths  of 
worms  that  they  should  first  be  moistened  and 
softened;  and  fresh  leaves,  however  soft  and 
tender  they  may  be,  are  similarly  treated,  prob- 
ably from  habit.  The  result  is  that  they  are 
partially  digested  before  they  are  taken  into 
the  alimentary  canal.  I any  not  aware  of  any 

* Claparede  doubts  whether  saliva  is  secreted  by  worms  : see 
“ Zeitschrift  fiir  wissenschaft.  Zoologie,”  B.  xix.  1869,  p.  601. 


44 


HABITS  OF  WORMS. 


Chap.  L 


other  case  of  extra-stomachal  digestion  hav- 
ing been  recorded.  The  boa-constrictor  bathes 
its  prey  with  saliva,  but  this  is  solely  for  lubri- 
cating it.  Perhaps  the  nearest  analogy  may 
be  found  in  such  plants  as  Drosera  and  Di- 
onaea;  for  here  animal  matter  is  digested  and 
converted  into  peptone  not  within  a stomach, 
but  on  the  surfaces  of  the  leaves. 

Calciferous  Glands. — These  glands  (see 
Fig.  i),  judging  from  their  size  and  from  their 
rich  supply  of  blood-vessels,  must  be  of  much 
importance  to  the  animal.  But  almost  as 
many  theories  have  been  advanced  on  their 
use  as  there  have  been  observers.  They  con- 
sist of  three  pairs,  which  in  the  common  earth- 
worm debouch  into  the  alimentary  canal  in 
advance  of  the  gizzard,  but  posteriorly  to  it 
in  Urochtaea  and  some  other  genera.*  The 
two  posterior  pairs  are  formed  by  lamellae, 
which  according  to  Claparede,  are  diverticula 
from  the  oesophagus. f These  lamellae  are 

coated  with  a pulpy  cellular  layer,  with  the 

* Perrier,  “ Archives  de  Zoolog.  exper.,”  July,  1874,  pp.  416, 
419. 

f “ Zeitschrift  fiir  wissenschaft.  Zoologie,”  B.  xix.  1869,  pp. 
603-606. 


Chap.  I. 


CALCIFEROUS  GLANDS. 


45 


outer  cells  lying  free  in  infinite  numbers.  If 
one  of  these  glands  is  punctured  and  squeezed, 
a quantity  of  white  pulpy  matter  exudes,  con- 
sisting of  these  free  cells.  They  are  minute, 
and  vary  in  diameter  from  2 to  6 ^ They 
contain  in  their  centres  a little  excessively  fine 
granular  matter;  but  they  look  so  like  oil  glob- 
ules that  Claparede  and  others  at  first  treated 
them  with  ether.  This  produces  no  effect;  but 
they  are  quickly  dissolved  with  effervescence 
in  acetic  acid,  and  when  oxalate  of  ammonia  is 
added  to  the  solution  a white  precipitate  is 
thrown  down.  We  may  therefore  conclude 
that  they  contain  carbonate  <\y  lime.  If  the 
cells  are  immersed  in  a very  little  acid,  they 
become  more  transparent,  look  like  ghosts, 
and  are  soon  lost  to  view;  but  if  much  acid 
is  added,  they  disappear  instantly.  After  a 
very  large  number  have  been  dissolved,  a floc- 
culent  residue  is  left,  which  apparently  con- 
sists of  the  delicate  ruptured  cell-walls.  In 
the  two  posterior  pairs  of  glands  the  carbonate 
of  lime  contained  in  the  cells  occasionally  ag- 
gregates into  small  rhombic  crystals  or  into 
concretions,  which  lie  between  the  lamellae; 


46 


HABITS  OF  WORMS. 


Chap.  I. 


but  I have  seen  only  one,  and  Claparede  only 
a very  few  such  cases. 

The  two  anterior  glands  differ  a little  in 
shape  from  the  four  posterior  ones,  by  being 
more  oval.  They  differ  also  conspicuously  in 
generally  containing  several  small,  or  two  or 
three  larger,  or  a single  very  large  concretion 
of  carbonate  of  lime,  as  much  as  ijmm.  in 
diameter.  When  a gland  includes  only  a few 
very  small  concretions,  or,  as  sometimes  hap- 
pens,  none  at  all,  it  is  easily  overlooked.  The 
large  concretions  are  round  or  oval,  and  exte- 
riorly almost  smooth.  One  was  found  which 
filled  up  not  only  the  whole  gland,  as  is  often 
the  case,  but  its  neck;  so  that  it  resembled  an 
olive-oil  flask  in  shape.  These  concretions 
when  broken  are  seen  to  be  more  or  less  crys- 
talline in  structure.  How  they  escape  from  the 
gland  is  a marvel;  but  that  they  do  escape  is 
certain,  for  they  are  often  found  in  the  gizzard, 
intestines,  and  in  the  castings  of  worms,  both 
with  those  kept  in  confinement  and  those  in  a 
state  of  nature. 

Claparede  says  very  little  about  the  struc- 
ture of  the  two  anterior  glands,  and  he  sup- 


Chap.  I. 


CALCIFEROUS  GLANDS. 


47 


poses  that  the  calcareous  matter  of  which  the 
concretions  are  formed  is  derived  from  the 
four  posterior  glands.  But  if  an  anterior  gland 
which  contains  only  small  concretions  is  placed 
in  acetic  acid  and  afterwards  dissected,  or  if 
sections  are  made  of  such  a gland  without 
being  treated  with  acid,  lamellae  like  those  in 
the  posterior  glands  and  coated  with  cellular 
matter  could  be  plainly  seen,  together  with  a 
multitude  of  free  calciferous  cells  readily  solu- 
ble in  acetic  acid.  When  a gland  is  completely 
filled  with  a single  large  concretion,  there  are 
no  free  cells,  as  these  have  been  all  consumed 
in  forming  the  concretion.  But  if  such  a con- 
cretion, or  one  of  only  moderately  large  size 
is  dissolved  in  acid,  much  membranous  matter 
is  left,  which  appears  to  consist  of  the  remains 
of  the  formerly  active  lamellae.  After  the 
formation  and  expulsion  of  a large  concretion, 
new  lamellae  must  be  developed  in  some  man- 
ner. In  one  section  made  by  my  son,  the 
process  had  apparently  commenced,  although 
the  gland  contained  two  rather  large  concre- 
tions, for  near  the  walls  several  cylindrical  and 
oval  pipes  were  intersected,  which  were  lined 


48 


HABITS  OF  WORMS. 


Chap.  I. 


with  cellular  matter  and  were  quite  filled  with 
free  calciferous  cells.  A great  enlargement  in 
one  direction  of  several  oval  pipes  would  give 
rise  to  the  lamellae. 

Besides  the  free  calciferous  cells  in  which 
no  nucleus  was  visible,  other  and  rather  larger 
free  cells  were  seen  on  three  occasions;  and 
these  contained  a distinct  nucleus  and  nucle- 
olus. They  were  only  so  far  acted  on  by  acetic 
acid  that  the  nucleus  was  thus  rendered  more 
distinct.  A very  small  concretion  was  removed 
from  between  two  of  the  lamellae  within  an 
anterior  gland.  It  was  embedded  in  pulpy 
cellular  matter,  with  many  free  calciferous 
cells,  together  with  a multitude  of  the  larger, 
free,  nucleated  cells,  and  these  latter  cells  were 
not  acted  on  by  acetic  acid,  while  the  former 
were  dissolved.  From  this  and  other  such 
cases  I am  led  to  suspect  that  the  calciferous 
cells  are  developed  from  the  larger  nucleated 
ones;  but  how  this  is  effected  was  not  ascer- 
tained. 

When  an  anterior  gland  contains  several 
minute  concretions,  some  of  these  are  general- 
ly angular  or  crystalline  in  outline,  while  the 


Chap.  I. 


CALCIFEROUS  GLANDS. 


49 


greater  number  are  rounded  .with  an  irregu- 
lar mulberry-like  surface.  Calciferous  cells  ad- 
hered to  many  parts  of  these  mulberry-like 
masses,  and  their  gradual  disappearance  could 
be  traced  while  they  still  remained  attached. 
It  was  thus  evident  that  the  concretions  are 
formed  from  the  lime  contained  within  the 
free  calciferous  cells.  As  the  smaller  concre- 
tions increase  in  size,  they  come  into  contact 
and  unite,  thus  enclosing  the  now  functionless 
lamellae;  and  by  such  steps  the  formation  of 
the  largest  concretions  could  be  followed. 
Why  the  process  regularly  takes  place  in  the 
two  anterior  glands,  and  only  rarely  in  the 
four  posterior  glands  is  quite  unknown. 
Morren  says  that  these  glands  disappear  dur- 
ing the  winter;  and  I have  seen  some  instances 
of  this  fact,  and  others  in  which  either  the  an- 
terior or  posterior  glands  were  at  this  season 
so  shrunk  and  empty,  that  they  could  be  dis- 
tinguished only  with  much  difficulty. 

With  respect  to  the  function  of  the  cal- 
ciferous glands,  it  is  prqbafble  that  they  pri- 
marily serve  as  organs  of  excretion,  and  sec- 
ondarily as  an  aid  to  digestion.  Worms  con- 


50 


HABITS  OF  WORMS. 


Chap.  I. 


sume  many  fallen  leaves;  and  it  is  known  that 
lime  goes  on  accumulating  in  leaves  until  they 
drop  off  the  parent-plant,  instead  of  being  re- 
absorbed into  the  stem  or  roots,  like  various 
other  organic  and  inorganic  substances.*  The 
ashes  of  a leaf  of  an  acacia  have  been  known 
to  contain  as  much  as  72  per  cent,  of  lime. 
Worms  therefore  would  be  liable  to  become 
charged  with  this  earth,  unless  there  were  some 
special  means  for  its  excretion;  and  the  cal- 
ciferous  glands  are  well  adapted  for  this  pur- 
pose. The  worms  which  live  in  mould  close 
over  the  chalk,  often  have  their  intestines  filled 
with  this  substance,  and  their  castings  are  al- 
most white.  Here  it  is  evident  that  the  supply 
of  calcareous  matter  must  be  superabundant. 
Nevertheless  with  several  worms  collected  on 
such  a site,  the  calciferous  glands  contained 
as  many  free  calciferous  cells,  and  fully  as  many 
and  large  concretions,  as  did  the  glands  of 
worms  which  lived  where  there  was  little  or 
no  lime;  and  this  indicates  that  the  lime  is  an 
excretion,  and  not  a secretion  poured  into  the 
alimentary  canal  for  some  special  purpose. 

* De  Vries,  “ Landwirth.  Jahrbiicher,”  1881,  p.  77. 


Chap.  I. 


CALCIFEROUS  GLANDS. 


51 


On  the  other  hand,  the  following  consid- 
erations render  it  highly  probable  that  the  car- 
bonate of  lime,  which  is  excreted  by  th^^lands, 
aids  the  digestive  process  unde£  ordinary  cir- 
cumstances. Leaves  during  their  decay  gen- 
erate an  abundance  of  various  kinds  of  acids, 
which  have  been  grouped  together  under  the 
term  of  humus  acids.  We  shall  have  to  recur 
to  this  subject  in  our  fifth  chapter,  and  I need 
here  only  say  that  these  acids  act  strongly  on 
carbonate  of  lime.  The  half-decayed  leaves 
which  are  swallowed  in  such  large  quantities 
by  worms  would,  therefore,  after  they  have 
been  moistened  and  triturated  in  the  alimen- 
tary canal,  be  apt  to  produce  such  acids.  And 
in  the  case  of  several  worms,  the  contents  of 
the  alimentary  canal  were  found  to  be  plainly 
acid,  as  shown  by  litmus  paper.  This  acidity 
cannot  be  attributed  to  the  nature  of  the  di- 
gestive fluid,  for  pancreatic  fluid  is  alkaline; 
and  we  have  seen  that  the  secretion  which  is 
poured  out  of  the  mouths  of  worms  for  the 
sake  of  preparing  the  leaves  for  consumption, 
is  likewise  alkaline.  The  acidity  can  hardly  be 
due  to  uric  acid,  as  the  contents  of  the  upper 


52 


HABITS  OF  WORMS. 


Chap.  I. 


part  of  the  intestine  were  often  acid.  In  one 
case  the  contents  of  the  gizzard  were  slightly 
acid,  those  of  the  upper  intestines  being  more 
plainly  acid.  In  another  case  the  contents  of 
the  pharynx  were  not  acid,  those  of  the  giz- 
zard doubtfully  so,  while  those  of  the  intestine 
were  distinctly  acid  at  a distance  of  5 cm. 
below  the  gizzard.  Even  with  the  higher 
herbivorous  and  omnivorous  animals,  the  con- 
tents of  the  large  intestine  are  acid.  “ This, 
however,  is  not  caused  by  any  acid  secretion 
from  the  mucous  membrane;  the  reaction  of 
the  intestinal  walls  in  the  larger  as  in  the  small 
intestine  is  alkaline.  It  must  therefore  arise 
from  acid  fermentations  going  on  in  the  con- 
tents themselves.  ...  In  Carnivora  the  con- 
tents of  the  caecum  are  said  to  be  alkaline,  and 
naturally  the  amount  of  fermentation  will  de- 
pend largely  on  the  nature  of  the  food.”  * 
With  worms  not  only  the  contents  of  the 
intestines,  but  their  ejected  matter  or  the  cast- 
ings, are  generally  acid.  Thirty  castings  from 
different  places  were  tested,  and  with  three  or 

* M.  Foster,  “ A Text-Book  of  Physiology,”  2nd  edit.  1878, 
P-  243. 


Chap.  I. 


CALCIFEROUS  GLANDS. 


53 


four  exceptions  were  found  to  be  acid;  and 
the  exceptions  may  have  been  due  to  such 
castings  not  having  been  recently  ejected;  for 
some  which  were  at  first  acid,  were  on  the  fol- 
lowing morning,  after  being  dried  and  again 
moistened,  no  longer  acid;  and  this  probably 
resulted  from  the  humus  acids  being,  as  is 
known  to  be  the  case,  easily  decomposed.  Five 
fresh  castings  from  worms  which  lived  in 
mould  close  over  the  chalk,  were  of  a whitish 
colour  and  abounded  with  calcareous  matter; 
and  these  were  not  in  the  least  acid.  This 
shows  how  effectually  carbonate  of  lime  neu- 
tralises the  intestinal  acids.  When  worms  were 
kept  in  pots  filled  with  fine  ferruginous  sand, 
it  was  manifest  that  the  oxide  of  iron,  with 
which  the  grains  of  silex  were  coated,  had  been 
dissolved  and  removed  from  them  in  the  cast- 
ings. 

The  digestive  fluid  of  worms  resembles  in 
its  action,  as  already  stated,  the  pancreatic 
secretion  of  the  higher  animals;  and  in  these 
latter,  “ pancreatic  digestion  is  essentially  alka- 
line; the  action  will  not  take  place  unless  some 
alkali  be  present;  and  the  activity  of  an  alka- 


54 


HABITS  OF  WORMS. 


Chap.  I. 


line  juice  is  arrested  by  acidification,  and  hin- 
dered by  neutralization.”  * Therefore  it  seems 
highly  probable  that  the  innumerable  calciier- 
ous  cells,  which  are  poured  from  the  foiir  pos- 
terior glands  into  the  alimentary  canal  of 
worms,  serve  to  neutralise  more  or  less  com- 
pletely the  acids  there  generated  Not  the  half- 
decayed  leaves.  We  have  seen  that  these  cells 
are  instantly  dissolved  by  a small  quantity  of 
acetic  acid,  and  as  they  do  not  always  suffice  to 
neutralise  the  contents  of  even  the  upper  part 
of  the  alimentary  canal,  the  lime  is  perhaps 
aggregated  into  concretions  in  the  anterior 
pair  of  glands,  in  order  that  some  may  be  car- 
ried down  to  the  posterior  parts  of  the  intes- 
tine, where  these  concretions  would  be  rolled 
about  amongst  the  acid  contents.  The  con- 
cretions found  in  the  intestines  and  in  the 
castings  often  have  a worn  appearance,  but 
whether  this  is  due  to  some  amount  of  attri- 
tion or  of  chemical  corrosion  could  not  be  told. 
Claparede  believes  that  they  are  formed  for 
the  sake  of  acting  as  mill-stones,  and  of  thus 
aiding  in  the  trituration  of  the  food.  They 

* M.  Foster,  Ibid.  p.  200. 


Chap.  I. 


CALCIFEROUS  GLANDS. 


55 


may  give  some  aid  in  this  way;  but  I fully  agree 
with  Perrier  that  this  must  be  of  quite  subor- 
dinate importance,  seeing  that  the  object  is 
already  attained  by  stones  being  generally 
present  in  the  gizzards  and  intestines  of  worms. 


CHAPTER  II. 


habits  of  worms — continued. 

Manner  in  which  worms  seize  objects — Their  power  of  suction — 
The  instinct  of  plugging  up  the  mouths  of  their  burrows — 
Stones  piled  over  the  burrows — The  advantages  thus  gained — - 
Intelligence  shown  by  worms  in  their  manner  of  plugging  up 
their  burrows — Various  kinds  of  leaves  and  other  objects  thus 
used — Triangles  of  paper — Summary  of  reasons  for  believing 
that  worms  exhibit  some  intelligence — Means  by  which  they 
excavate  their  burrows,  by  pushing  away  the  earth  and  swal- 
lowing it — Earth  also  swallowed  for  the  nutritious  matter 
which  it  contains — Depth  to  which  worms  burrow,  and  the 
construction  of  their  burrows — Burrows  lined  with  castings, 
and  in  the  upper  part  with  leaves — The  lowest  part  paved  with 
little  stones  or  seeds — Manner  in  which  the  castings  are 
ejected — The  collapse  of  old  burrows — Distribution  of  worms 
— Tower-like  castings  in  Bengal — Gigantic  castings  on  the 
Nilgiri  Mountains — Castings  ejected  in  all  countries. 

In  the  pots  in  which  worms  were  kept, 
leaves  were  pinned  down  to  the  soil,  and  at 
night  the  manner  in  which  they  were  seized 
could  be  observed.  The  worms  always  en- 
deavoured to  drag  the  leaves  towards  their 
burrows;  and  they  tore  or  sucked  off  small 

fragments,  whenever  the  leaves  were  sufficient- 

56 


Chap.  II.  THEIR  MANNER  OF  PREHENSION.  57 


ly  tender.  They  generally  seized  the  thin  edge 
of  a leaf  with  their  mouths,  between  the  pro- 
jecting upper  and  lower  lip;  the  thick  and 
strong  pharynx  being  at  the  same  time,  as 
Perrier  remarks,  pushed  forward  within  their 
bodies,  so  as  to  afford  a point  of  resistance  for 
the  upper  lip.  In  the  case  of  broad  flat  ob- 
jects they  acted  in  a wholly  different  manner. 
The  pointed  anterior  extremity  of  the  body, 
after  being  brought  into  contact  with  an  ob- 
ject of  this  kind,  was  drawn  within  the  adjoin- 
ing rings,  so  that  it  appeared  truncated  and  be- 
came as  thick  as  the  rest  of  the  body.  This 
part  could  then  be  seen  to  swell  a little;  and 
this,  I believe,  is  due  to  the  pharynx  being 
pushed  a little  forwards.  Then  by  a slight 
withdrawal  of  the  pharynx  or  by  its  expansion, 
a vacuum  was  produced  beneath  the  truncated 
slimy  end  of  the  body  whilst  in  contact  with 
the  object;  and  by  this  means  the  two  adhered 
firmly  together.*  That  under  these  circum- 
stances a vacuum  was  produced  was  plainly 

* Clapar&de  remarks  (“  Zeitschrift  fur  wissenschaft.  Zoolog.” 
B.  19,  1869,  p.  602)  that  the  pharynx  appears  from  its  structure 
to  be  adapted  for  suction. 

5 


58 


HABITS  OF  WORMS. 


Chap.  II. 


seen  on  one  occasion,  when  a large  worm 
lying  beneath  a flaccid  cabbage  leaf  tried  to 
drag  it  away;  for  the  surface  of  the  leaf  di- 
rectly over  the  end  of  the  worm’s  body  became 
deeply  pitted.  On  another  occasion  a worm 
suddenly  lost  its  hold  on  a flat  leaf;  and  the  an- 
terior end  of  the  body  was  momentarily  seen 
to  be  cup-formed.  Worms  can  attach  them- 
selves to  an  object  beneath  water  in  the  same 
manner;  and  I saw  one  thus  dragging  away  a 
submerged  slice  of  an  onion-bulb. 

The  edges  of  fresh  or  nearly  fresh  leaves 
affixed  to  the  ground  were  often  nibt^ed  by 
the  worms;  and  sometimes  the  epidermis  and 
all  the  parenchyma  on  one  side  was  gnawed 
completely  away  over  a considerable  space; 
the  epidermis  alone  on  the  opposite  side  being 
left  quite  clean.  The  veins  were  never  touched, 
and  leaves  were  thus  sometimes  partly  con- 
verted into  skeletons.  As  worms  have  no 
teeth  and  as  their  mouths  consist  of  very  soft 
tissue,  it  may  be  presumed  that  they  consume 
by  means  of  suction  the  edges  aqd  the  par- 
enchyma of  fresh  leaves,  after  they^^ave  been 
softened  by  the  digestive  fluid.  They  cannot 


Chap.  II.  PROTECTION  OF  THEIR  BURROWS.  59 


attack  such  strong  leaves  as  those  of  sea-kale 
or  large  and  thick  leaves  of  ivy;  though  one 
of  the  latter  after  it  had  become  rotten  was 
reduced  in  parts  to  the  state  of  a skeleton. 

Worms  seize  leaves  and  other  objects,  not 
only  to  serve  as  food,  but  for  plugging  up  the 
mouths  of  their  burrows;  and  this  is  one  of 
their  strongest  instincts.  Leaves  and  petioles 
of  many  kinds,  some  flower-peduncles,  often 
decayed  twigs  of  trees,  bits  of  paper,  feathers, 
tufts  of  wool  and  horse-hairs  are  dragged  into 
their  burrows  for  this  purpose.  I have  seen 
as  many  as  seventeen  petioles  of  a Clematis 
projecting  from  the  mouth  of  one  burrow,  and 
ten  from  the  mouth  of  another.  Some  of  these 
objects,  such  as  the  petioles  just  named,  feath- 
ers, &c.,  are  never  gnawed  by  worms.  In  a 
gravel  walk  in  my  garden  I found  many  hun- 
dred leaves  of  a pine-tree  (P.  austriaca  or 
nigricans)  drawn  by  their  bases  into  burrows. 
The  surfaces  by  which  these  leaves  are  articu- 
lated to  the  branches  are  shaped  in  as  pecul- 
iar a manner  as  is  the  joint  between  the  leg- 
bones  of  a quadruped;  and  if  these  surfaces 
had  been  in  the  least  gnawed,  the  fact  would 


6o 


HABITS  OF  WORMS. 


Chap.  II. 


have  been  immediately  visible,  but  there  was 
no  trace  of  gnawing.  Of  ordinary  dicotyle- 
donous leaves,  all  those  which  are  dragged 
into  burrows  are  not  gnawed.  I have  seen  as 
many  as  nine  leaves  of  the  lime-tree  drawn 
into  the  same  burrow,  and  not  nearly  all  of 
them  had  been  gnawed;  but  such  leaves  may 
serve  as  a store  for  future  consumption. 
Where  fallen  leaves  are  abundant,  many  more 
are  sometimes  collected  over  the  mouth  of  a 
burrow  than  can  be  used,  so  that  a small  pile 
of  unused  leaves  is  left  like  a roof  over  those 
which  have  been  partly  dragged  in. 

A leaf  in  being  dragged  a little  way  into 
a cylindrical  burrow  is  necessarily  much  folded 
or  crumpled.  When  another  leaf  is  drawn  in, 
this  is  done  exteriorly  to  the  first  one,  and  so 
on  with  the  succeeding  leaves;  and  finally  all 
become  closely  folded  and  pressed  together. 
Sometimes  the  worm  enlarges  the  mouth  of 
its  burrow,  or  makes  a fresh  one  close  by,  so 
as  to  draw  in  a still  larger  number  of  leaves. 
They  often  or  generally  fill  up  the  interstices 
between  the  drawn-in  leaves  with  moist  viscid 
earth  ejected  from  their  bodies,  and  thus  the 


Chap.  II.  PROTECTION  OF  THEIR  BURROWS.  6 1 


mouths  of  the  burrows  are  securely  plugged. 
Hundreds  of  such  plugged  burrows  may  be 
seen  in  many  places,  especially  during  the 
autumnal  and  early  winter  months.  But,  as 
will  hereafter  be  shown,  leaves  are  dragged 
into  the  burrows  not  only  for  plugging  them 
up  and  for  food,  but  for  the  sake  of  lining  the 
upper  part  or  mouth. 

When  worms  cannot  obtain  leaves,  peti- 
oles, sticks,  &c.,  with  which  to  plug  up  the 
mouths  of  their  burrows,  they  often  protect 
them  by  little  heaps  of  stones;  and  such  heaps 
of  smooth  rounded  pebbles  may  frequently  be 
seen  on  gravel-walks.  Here  there  can  be  no 
question  about  food.  A lady,  who  was  inter- 
ested in  the  habits  of  worms,  removed  the  little 
heaps  of  stones  from  the  mouths  of  several 
burrows  and  cleared  the  surface  of  the  ground 
for  some  inches  all  round.  She  went  out  on 
the  following  night  with  a lantern,  and  saw 
the  worms  with  their  tails  fixed  in  their  bur- 
rows, dragging  the  stones  inwards  by  the  aid 
of  their  mouths,  no  doubt  by  suction.  “ After 
two  nights  some  of  the  holes  had  8 or  9 small 
stones  over  them;  after  four  nights  one  had 


62 


HABITS  OF  WORMS. 


Chap.  II. 


about  30,  and  another  34  stones.”  * One 
stone  which  had  been  dragged  over  the  gravel- 
walk  to  the  mouth  of  a burrow  weighed  two 
ounces;  and  this  proves  how  strong  worms 
are.  But  they  show  greater  strength  in  some- 
times displacing  stones  in  a well-trodden 
gravel-walk;  that  they  do  so,  may  be  inferred 
from  the  cavities  left  by  the  displaced  stones 
being  exactly  filled  by  those  lying  over  the 
mouths  of  adjoining  burrows,  as  I have  my- 
self observed. 

Work  of  this  kind  is  usually  performed 
during  the  night;  but  I have  occasionally 
known  objects  to  be  drawn  into  the  burrows 
during  the  day.  What  advantage  the  worms 
derive  from  plugging  up  the  mouths  of  their 
burrows  with  leaves,  &c.,  or  from  piling 
stones  over  them,  is  doubtful.  They  do  not 
act  in  this  manner  at  the  times  when  they 
eject  much  earth  from  their  burrows;  for  their 
castings  then  serve  to  cover  the  mouth. 
When  gardeners  wish  to  kill  worms  on  a lawn, 
it  is  necessary  first  to  brush  or  rake  away  the 

* An  account  of  her  observations  is  given  in  the  “ Gardeners’ 
Chronicle,”  March  28th,  1868,  p.  324. 


Chap.  II.  PROTECTION  OF  THEIR  BURROWS.  63 

castings  from  the  surface,  in  order  that  the 
lime-water  may  enter  the  burrows.*  It  might 
be  inferred  from  this  fact  that  the  mouths  are 
plugged  up  with  leaves,  &c.,  to  prevent  the 
entrance  of  water  during  heavy  rain;  but  it 
may  be  urged  against  this  view  that  a few, 
loose,  well-rounded  stones  are  ill-adapted  to 
keep  out  water.  I have  moreover  seen  many 
burrows  in  the  perpendicularly  cut  turf-edg- 
ings to  gravel-walks,  into  which  water  could 
hardly  flow,  as  well  plugged  as  burrows  on  a 
level  surface.  Can  the  plugs  or  piles  of  stones 
aid  in  concealing  the  burrows  from  scolopen- 
ders,  which,  according  to  Hoffmeister,f  are 
the  bitterest  enemies  of  worms?  Or  may  not 
worms  when  thus  protected  be  able  to  remain 
with  safety  with  their  heads  close  to  the 
mouths  of  their  burrows,  which  we  know  that 
they  like  to  do,  but  which  costs  so  many  of 
them  their  lives?  Or  may  not  the  plugs  check 
the  free  ingress,  of  the  lowest  stratum  of  air, 
when  chilled  by  radiation  at  night,  from  the 
surrounding  ground  and  herbage.  I am  in- 

* London’s  “ Gard.  Mag.,”  xvii.  p.  216,  as  quoted  in  the 
“Catalogue  of  the  British  Museum  Worms,”  1865,  p.  327. 

f “Familie  der  Regenwiirmer,”  p.  19. 


6 4 


HABITS  OF  WORMS. 


Chap.  II. 


dined  to  believe  in  this  latter  view;  firstly,  be- 
cause when  worms  were  kept  in  pots  in  a 
room  with  a fire,  in  which  case  cold  air  could 
not  enter  the  burrows,  they  plugged  them  up 
in  a slovenly  manner;  and  secondarily,  because 
they  often  coat  the  upper  part  of  their  bur- 
rows with  leaves,  apparently  to  prevent  their 
bodies  from  coming  into  close  contact  with 
the  cold  damp  earth.  But  the  plugging-up 
process  may  perhaps  serve  for  all  the  above 
purposes. 

Whatever  the  motive  may  be,  it  appears 
that  worms  much  dislike  leaving  the  mouths 
of  their  burrows  open.  Nevertheless  they  will 
reopen  them  at  night,  whether  or  not  they 
can  afterwards  close  them.  Numerous  open 
burrows  may  be  seen  on  recently-dug  ground, 
for  in  this  case  the  worms  eject  their  castings 
in  cavities  left  in  the  ground,  or  in  the  old  bur- 
rows, instead  of  piling  them  over  the  mouths 
of  their  burrows,  and  they  cannot  collect  ob- 
jects on  the  surface  by  which  the  mouths 
might  be  protected.  So  again  on  a recently 
disinterred  pavement  of  a Roman  villa  at 
Abinger  (hereafter  to  be  described)  the  worms 


Chap.  II. 


THEIR  INTELLIGENCE. 


65 


pertinaciously  opened  their  burrows  almost 
every  night,  when  these  had  been  closed  by 
being  trampled  on,  although  they  were  rarely 
able  to  find  a few  minute  stones  wherewith  to 
protect  them. 

Intelligence  shown 
ner  of  plugging  up  their  burrows . — If  a man  had 
to  plug  up  a small  cylindrical  hole,  with  such 
objects  as  leaves,  petioles  or  twigs,  he  would 
drag  or  push  them  in  by  their  pointed  ends; 
but  if  these  objects  were  very  thin  relatively 
to  the  size  of  the  hole,  he  would  probably  in- 
sert some  by  their  thicker  or  broader  ends. 
The  guide  in  his  case  would  be  intelligence. 
It  seemed  therefore  worth  while  to  observe 
carefully  how  worms  dragged  leaves  into  their 
burrows;  whether  by  their  tips  or  bases  or 
middle  parts.  It  seemed  more  especially  de- 
sirable to  do  this  in  the  case  of  plants  not  na- 
tives to  our  country;  for  although  the  habit 
of  dragging  leaves  into  their  burrows  is  un- 
doubtedly instinctive  with  worms,  yet  instinct 
could  not  tell  them  how  to  act  in  the  case  of 
leaves  about  which  their  progenitors  knew 
nothing.  If,  moreover,  worms  acted  solely 


worms  in  their  man- 


66 


HABITS  OF  WORMS. 


Chap.  II. 


through  instinct  or  an  unvarying  inherited  im- 
pulse, they  would  draw  all  kinds  of  leaves  into 
their  burrows  in  the  same  manner.  If  they 
have  no  such  definite  instinct,  we  might  ex- 
pect that  chance  would  determine  whether  the 
tip,  base  or  middle  was  seized.  If  both  these 
alternatives  are  excluded,  intelligence  alone  is 
left;  unless  the  worm  in  each  case  first  tries 
many  different  methods,  and  follows  that  alone 
which  proves  possible  or  the  most  easy;  but  to 
act  in  this  manner  and  to  try  different  meth- 
ods makes  a near  approach  to  intelligence. 

In  the  first  place  227  withered  leaves  of 
various  kinds,  mostly  of  English  plants,  were 
pulled  out  of  worm-burrows  in  several  places. 
Of  these,  181  had  been  drawn  into  the  bur- 
rows by  or  near  their  tips,  so  that  the  foot- 
stalk projected  nearly  upright  from  the  mouth 
of  the  burrow;  20  had  been  drawn  in  by  their 
bases,  and  in  this  case  the  tips  projected  from 
the  burrows;  and  26  had  been  seized  near  the 
middle,  so  that  these  had  been  drawn  in  trans- 
versely and  were  much  crumpled.  Therefore 
80  per  cent,  (always  using  the  nearest  whole 
number)  had  been  drawn  in  by  the  tip,  9 per 


Chap.  II. 


THEIR  INTELLIGENCE. 


67 


cent,  by  the  base  or  footstalk,  and  1 1 per  cent, 
transversely  or  by  the  middle.  This  alone  is 
almost  sufficient  to  show  that  chance  does  not 
determine  the  manner  in  which  leaves  are 
dragged  into  the  burrows. 

Of  the  above  227  leaves,  70  consisted  of 
the  fallen  leaves  of  the  common  lime-tree, 
which  is  almost  certainly  not  a native  of  Eng- 
land. These  leaves  are  much  acuminated  to- 
wards the  tip,  and  are  very  broad  at  the  base 
with  a well-developed  foot-stalk.  They  are 
thin  and  quite  flexible  when  half-withered.  Of 
the  70,  79  per  cent,  had  been  drawn  in  by  or 
near  the  tip;  4 per  cent,  by  or  near  the  base; 
and  17  per  cent,  transversely  or  by  the  mid- 
dle. These  proportions  agree  very  closely,  as 
far  as  the  tip  is  concerned,  with  those  before 
given.  But  the  percentage  drawn  in  by  the 
base  is  smaller,  which  may  be  attributed  to 
the  breadth  of  the  basal  part  of  the  blade. 
We  here,  also,  see  that  the  presence  of  a foot- 
stalk, which  it  might  have  been  expected  would 
have  tempted  the  worms  as  a convenient 
handle,  has  little  or  no  influence  in  determin- 
ing the  manner  in  which  lime  leaves  are 


68 


HABITS  OF  WORMS. 


Chap.  II. 


dragged  into  the  burrows.  The  considerable 
proportion,  viz.,  17  per  cent.,  drawn  in  more 
or  less  transversely  depends  no  doubt  on  the 
flexibility  of  these  half-decayed  leaves.  The 
fact  of  so  many  having  been  drawn  in  by  the 
middle,  and  of  some  few  having  been  drawn 
in  by  the  base,  renders  it  improbable  that  the 
worms  first  tried  to  draw  in  most  of  the  leaves 
by  one  or  both  of  these  methods,  and  that 
they  afterwards  drew  in  79  per  cent,  by  their 
tips;  for  it  is  clear  that  they  would  not  have 
failed  in  drawing  them  in  by  the  base  or 
middle. 

The  leaves  of  a foreign  plant  were  next 
searched  for,  the  blades  of  which  were  not 
more  pointed  towards  the  apex  than  towards 
the  base.  This  proved  to  be  the  case  with 
those  of  a laburnum  (a  hybrid  between 
Cytisus  alpinus  and  laburnum ) for  on  doubling 
the  terminal  over  the  basal  half,  they  gener- 
ally fitted  exactly;  and  when  there  was  any 
difference,  the  basal  half  was  a little  the  nar- 
rower. It  might,  therefore,  have  been  ex- 
pected that  an  almost  equal  number  of  these 
leaves  would  have  been  drawn  in  by  the  tip 


Chap.  II.  THEIR  INTELLIGENCE.  69 

and  base,  or  a slight  excess  in  favour  of  the 
latter.  But  of  73  leaves  (not  included  in  the 
first  lot  of  227)  pulled  out  of  worm-burrows, 
63  per  cent,  had  been  drawn  in  by  the  tip;  27 
per  cent,  by  the  base,  and  10  per  cent,  trans- 
versely. We  here  see  that  a far  larger  pro- 
portion, viz.,  27  per  cent,  were  drawn  in  by 
the  base  than  in  the  case  of  lime  leaves,  the 
blades  of  which  are  very  broad  at  the  base, 
and  of  which  only  4 per  cent,  had  thus  been 
drawn  in.  We  may  perhaps  account  for  the 
fact  of  a still  larger  proportion  of  the  laburnum 
leaves  not  having  been  drawn  in  by  the  base, 
by  worms  having  acquired  the  habit  of  gen- 
erally drawing  in  leaves  by  their  tips  and  thus 
avoiding  the  foot-stalk.  For  the  basal  mar- 
gin of  the  blade  in  many  kinds  of  leaves  forms 
a large  angle  with  the  foot-stalk;  and  if  such 
a leaf  were  drawn  in  by  the  foot-stalk,  the 
basal  margin  would  come  abruptly  into  con- 
tact with  the  ground  on  each  side  of  the  bur- 
row, and  would  render  the  drawing  in  of  the 
leaf  very  difficult. 

Nevertheless  worms  break  through  their 
habit  of  avoiding  the  foot-stalk,  if  this  part 


yo  HABITS  OF  WORMS.  Chap.  II. 

offers  them  the  most  convenient  means  for 
drawing  leaves  into  their  burrows.  The  leaves 
of  the  endless  hybridised  varieties  of  the 
Rhododendron  vary  much  in  shape;  some  are 
narrowest  towards  the  base  and  others  to- 
wards the  apex.  After  they  have  fallen  off, 
the  blade  on  each  side  of  the  midrib  often  be- 
comes curled  up  while  drying,  sometimes  along 
the  whole  length,  sometimes  chiefly  at  the 
base,  sometimes  towards  the  apex.  Out  of  28 
fallen  leaves  on  one  bed  of  peat  in  my  garden, 
no  less  than  23  were  narrower  in  the  basal 
quarter  than  in  the  terminal  quarter  of  their 
length;  and  this  narrowness  was  chiefly  due  to 
the  curling  in  of  the  margins.  Out  of  36  fallen 
leaves  on  another  bed,  in  which  different  varie- 
ties of  the  Rhododendron  grew,  only  17  were 
narrower  towards  the  base  than  towards  the 
apex.  My  son  William,  who  first  called  my 
attention  to  this  case,  picked  up  237  fallen 
leaves  in  his  garden  (where  the  Rhododendron 
grows  in  the  natural  soil)  and  of  these  65  per 
cent,  could  have  been  drawn  by  worms  into 
their  burrows  more  easily  by  the  base  or  foot- 
stalk than  by  the  tip;  and  this  was  partly  due 


Chap.  II. 


THEIR  INTELLIGENCE. 


71 


to  the  shape  of  the  leaf  and  in  a less  degree  to 
the  curling  in  of  the  margins:  27  per  cent, 
could  have  been  drawn  in  more  easily  by  the 
tip  than  by  the  base:  and  8 per  cent,  with  about 
equal  ease  by  either  end.  The  shape  of  a fallen 
leaf  ought  to  be  judged  of  before  one  end  has 
been  drawn  into  a burrow,  for  after  this  has 
happened,  the  free  end,  whether  it  be  the  base 
or  apex,  will  dry  more  quickly  than  the  end 
embedded  in  the  damp  ground;  and  the  ex- 
posed margins  of  the  free  end  will  consequent- 
ly tend  to  become  more  curled  inwards  than 
they  were  when  the  leaf  was  first  seized  by  the 
worm.  My  son  found  91  leaves  which  had 
been  dragged  by  worms  into  their  burrows, 
though  not  to  a great  depth;  of  these  66  per 
cent,  had  been  drawn  in  by  the  base  or  foot- 
stalk; and  34  per  cent,  by  the  tip.  Jn  this  case, 
therefore,  the  worms  judged  with  a consider- 
ble  degree  of  correctness  how  b^st  to  draw  the 
withered  leaves  of  this  foreign  plant  into  their 
burrows;  notwithstanding  that  they  had  to  de- 
part  from  their  usual  h^bit  of  avoiding  the 
foot-stalk. 

On  the  gravel-walks  in  my  garden  a very 


72 


HABITS  OF  WORMS. 


Chap.  II. 


large  number  of  leaves  of  three  species  of 
Pinus  ( P . austriaca,  nigricans  and  sylvestris ) 
are  regularly  drawn  into  the  mouths  of  worm- 
burrows.  These  leaves  consist  of  two  needles, 
which  are  of  considerable  length  in  the  two 
first  and  short  in  the  last  named  species,  and 
are  united  to  a common  base;  and  it  is  by  this 
part  that  they  are  almost  invariably  drawn 
into  the  burrows.  I have  seen  only  two  or 
at  most  three  exceptions  to  this  rule  with 
worms  in  a state  of  nature.  As  the  sharply 
pointed  needles  diverge  a little,  and  as  several 
leaves  are  drawn  into  the  same  burrow,  each 
tuft  forms  a perfect  chevaux  de  frise.  On  two 
occasions  many  of  these  tufts  were  pulled  up 
in  the  evening,  but  by  the  following  morning 
fresh  leaves  had  been  pulled  in,  and  the  bur- 
rows were  again  well  protected.  These  leaves 
could  not  be  dragged  into  the  burrows  to  any 
depth,  except  by  their  bases,  as  a worm  can- 
not seize  hold  of  the  two  needles  at  the  same 
time,  and  if  one  alone  were  seized  by  the 
apex,  the  other  would  be  pressed  against  the 
ground  and  would  resist  the  entry  of  the  seized 
one.  This  was  manifest  in  the  above  men- 


Chap.  II. 


THEIR  INTELLIGENCE. 


73 


tioned  two  or  three  exceptional  cases.  In 
order,  therefore,  that  worms  should  do  their 
work  well,  they  must  drag  pine-leaves  into 
their  burrows  by  their  bases,  where  the  two 
needles  are  conjoined.  But  how  they  are 
guided  in  this  work  is  a perplexing  question. 

This  difficulty  led  my  son  Francis  and  my- 
self to  observe  worms  in  confinement  during 
several  nights  by  the  aid  of  a dim  light,  while 
they  dragged  the  leaves  of  the  above  named 
pines  into  their  burrows.  They  moved  the 
anterior  extremities  of  their  bodies  about  the 
leaves,  and  on  several  occasions  when  they 
touched  the  sharp  end  of  a needle  they  with- 
drew suddenly  as  if  pricked.  But  I doubt 
whether  they  were  hurt,  for  they  are  indiffer- 
ent to  very  sharp  objects,  and  will  swallow  even 
rose-thorns  and  small  splinters  of  glass.  It 
may  also  be  doubted,  whether  the  sharp  ends 
of  the  needles  serve  to  tell  them  that  this  is 
the  wrong  end  to  seize;  for  the  points  were 
cut  off  many  leaves  for  a length  of  about  one 
inch,  and  fifty-seven  of  them  thus  treated  were 
drawn  into  the  burrows  by  their  bases,  and  not 

one  by  the  cut-off  ends.  The  worms  in  con- 
6 


74  HABITS  OF  WORMS.  Chap.  II. 

finement  often  seized  the  needles  near  the  mid- 
dle and  drew  them  towards  the  mouths  of 
their  burrows;  and  one  worm  tried  in  a sense- 
less manner  to  drag  them  into  the  burrow  by 
bending  them.  They  sometimes  collected 
many  more  leaves  over  the  mouths  of  their 
burrows  (as  in  the  case  formerly  mentioned  of 
lime-leaves)  than  could  enter  them.  On  other 
occasions,  however,  they  behaved  very  differ- 
ently; for  as  soon  as  they  touched  the  base  of 
a pine-leaf,  this  was  seized,  being  sometimes 

* 

completely  engulfed  in  their  mouths,  or  a point 
very  near  the  base  was  seized,  and  the  leaf  was 
then  quickly  dragged  or  rather  jerked  into 
their  burrows.  It  appeared  both  to  my  son 
and  myself  as  if  the  worms  instantly  perceived 
as  soon  as  they  had  seized  a leaf  in  the  proper 
manner.  Nine  such  cases  were  observed,  but 
in  one  of  them  the  worm  failed  to  drag  the  leaf 
into  its  burrow,  as  it  was  entangled  by  other 
leaves  lying  near.  In  another  case  a leaf  stood 
nearly  upright  with  the  points  of  the  needles 
partly  inserted  into  a burrow,  but  how  placed 
there  was  not  seen;  and  then  the  worm  reared 
itself  up  and  seized  the  base,  which  was 


Chap.  II. 


THEIR  INTELLIGENCE. 


75 


dragged  into  the  mouth  of  the  burrow  by  bow- 
ing the  whole  leaf.  On  the  other  hand,  after 
a worm  had  seized  the  base  of  a leaf,  this  was 
on  two  occasions  relinquished  from  some  un- 
known motive. 

As  already  remarked,  the  habit  of  plugging 
up  the  mouths  of  the  burrows  with  various 
objects,  is  no  doubt  instinctive  in  worms;  and 
a very  young  one,  born  in  one  of  my  pots, 
dragged  for  some  little  distance  a Scotch-fir 
leaf,  one  needle  of  which  was  as  long  and  al- 
most as  thick  as  its  own  body.  No  species  of 
pine  is  endemic  in  this  part  of  England,  it  is 
therefore  incredible  that  the  proper  manner  of 
dragging  pine-leaves  into  the  burrows  can  be 
instinctive  with  our  worms.  But  as  the  worms 
on  which  the  above  observations  were  made, 
were  dug  up  beneath  or  near  some  pines,  which 
had  been  planted  there  about  forty  years,  it 
was  desirable  to  prove  that  their  actions  were 
not  instinctive.  Accordingly,  pine-leaves  were 
scattered  on  the  ground  in  places  far  removed 
from  any  pine-tree,  and  90  of  them  were  drawn 
into  the  burrows  by  their  bases.  Only  two 
were  drawn  in  by  the  tips  of  the  needles,  and 


76  HABITS  OF  WORMS.  Chap.  II. 

these  were  not  real  exceptions,  as  one  was 
drawn  in  for  a very  short  distance,  and  the 
two  needles  of  the  other  cohered.  Other  pine- 
leaves  were  given  to  worms  kept  in  pots  in  a 
warm  room,  and  here  the  result  was  different; 
for  out  of  42  leaves  drawn  into  the  burrows, 
no  less  than  16  were  drawn  in  by  the  tips  of 
the  needles.  These  worms,  however,  worked 
in  a careless  or  slovenly  manner;  for  the  leaves 
were  often  drawn  in  to  only  a small  depth; 
sometimes  they  were  merely  heaped  over  the 
mouths  of  the  burrows,  and  sometimes  none 
were  drawn  in.  I believe  that  this  carelessness 
may  be  accounted  for  by  the  air  of  the  room 
being  warm,  and  the  worms  consequently  not 
being  anxious  to  plug  up  their  holes  effectual- 
ly. Pots  tenanted  by  worms  and  covered  with 
a net  which  allowed  the  entrance  of  cold  air, 
were  left  out  of  doors  for  several  nights,  and 
now  72  leaves  were  all  properly  drawn  in  by 
their  bases. 

It  might  perhaps  be  inferred  from  the  facts 
as  yet  given,  that  worms  somehow  gain  a gen- 
eral notion  of  the  shape  or  structure  of  pine- 
leaves,  and  perceive  that  it  is  necessary  for 


Chap.  II.  THEIR  INTELLIGENCE.  77 

them  to  seize  the  base  where  the  two  needles 
are  conjoined.  But  the  following  cases  make 
this  more  than  doubtful.  The  tips  of  a large 
number  of  needles  of  P.  austriaca  were  ce- 
mented together  with  shell-lac  dissolved  in  al- 
cohol, and  were  kept  for  some  days,  until,  as 
I believe,  all  odour  or  taste  had  been  lost;  and 
they  were  then  scattered  on  the  ground  where 
no  pine-trees  grew,  near  burrows  from  which 
the  plugging  had  been  removed.  Such  leaves 
could  have  been  drawn  into  the  burrows  with 
equal  ease  by  either  end;  and  judging  from 
analogy  and  more  especially  from  the  case 
presently  to  be  given  of  the  petioles  of  Clematis 
montana , I expected  that  the  apex  would  have 
been  preferred.  But  the  result  was  that  out 
of  12 1 leaves  with  the  tips  cemented,  which 
were  drawn  into  burrows,  108  were  drawn  in 
by  their  bases,  and  only  13  by  their  tips. 
Thinking  that  the  worms  might  possibly  per- 
ceive and  dislike  the  smell  or  taste  of  the  shell- 
lac,  though  this  was  very  improbable,  especial- 
ly after  the  leaves  had  been  left  out  during 
several  nights,  the  tips  of  the  needles  of  many 
leaves  were  tied  together  with  fine  thread.  Of 


78 


HABITS  OF  WORMS. 


Chap.  II. 


leaves  thus  treated  150  were  drawn  into  bur- 
rows— 123  by  the  base  and  27  by  the  tied  tips; 
so  that  between  four  and  five  times  as  many 
were  drawn  in  by  the  base  as  by  the  tip.  It  is 
possible  that  the  short  cut-off  ends  of  the 
thread  with  which  they  were  tied,  may  have 
tempted  the  worms  to  drag  in  a larger  propor- 
tional number  by  the  tips  than  when  cement 
was  used.  Of  the  leaves  with  tied  and  ce- 
mented tips  taken  together  (271  in  number) 
85  per  cent,  were  drawn  in  by  the  base  and 
15  per  cent,  by  the  tips.  We  may  therefore 
infer  that  it  is  not  the  divergence  of  the  two 
needles  which  leads  worms  in  a state  of  nature 
almost  invariably  to  drag  pine-leaves  into  their 
burrows  by  the  base.  Nor  can  it  be  the  sharp- 
ness of  the  points  of  the  needles  which  deter- 
mines them;  for,  as  we  have  seen,  many  leaves 
with  the  points  cut  off  were  drawn  in  by  their 
bases.  We  are  thus  led  to  conclud^  that  with 
pine-leaves  there  must  be  somethin'g  attractive 
to  worms  in  the  base,  notwithstanding  that 
few  ordinary  leaves  are  drawn  in  by  the  base 
or  foot-stalk. 

Petioles. — We  will  now  turn  to  the  petioles 


Chap.  II. 


THEIR  INTELLIGENCE. 


79 


or  foot-stalks  of  compound  leaves,  after  the 
leaflets  have  fallen  off.  Those  from  Clematis 
montana , which  grew  over  a verandah,  were 
dragged  early  in  January  in  large  numbers 
into  the  burrows  on  an  adjoining  gravel-walk, 
lawn,  and  flower-bed.  These  petioles  vary 
from  2\  to  4^  inches  in  length,  are  rigid  and 
of  nearly  uniform  thickness,  except  close  to 
the  base  where  they  thicken  rather  abruptly, 
being  here  about  twice  as  thick  as  in  any  other 
part.  The  apex  is  somewhat  pointed,  but 
soon  withers  and  is  then  easily  broken,  off.  Of 
these  petioles,  314  were  pulled  out  of  burrows 
in  the  above  specified  sites;  and  it  was  found 
that  76  per  cent,  had  been  drawn  in  by  their 
tips,  and  24  per  cent,  by  their  bases;  so  that 
those  drawn  in  by  the  tip  were  a little  more 
than  thrice  as  many  as  those  drawn  in  by  the 
base.  Some  of  those  extracted  from  the  well- 
beaten  gravel-walk  were  kept  separate  from 
the  others;  and  of  these  (59  in  number)  nearly 
five  times  as  many  had  been  drawn  in  by  the 
tip  as  by  the  base;  whereas  of  those  extracted 
from  the  lawn  and  flower-bed,  where  from  the 
soil  yielding  more  easily,  less  care  would  be 


8o 


HABITS  OF  WORMS. 


Chap.  II. 


necessary  in  plugging  up  the  burrows,  the 
proportion  of  those  drawn  in  by  the  tip  (130) 
to  those  drawn  in  by  the  base  (48)  was  rather 
less  than  three  to  one.  That  these  petioles  had 
been  dragged  into  the  burrows  for  plugging 
them  up,  and  not  for  food,  was  manifest,  as 
neither  end,  as  far  as  I could  see,  had  been 
gnawed.  As  several  petioles  are  used  to  plug 
up  the  same  burrow,  in  one  case  as  many  as 
10,  and  in  another  case  as  many  as  15,  the 
worms  may  perhaps  at  first  draw  in  a few  by 
the  thicker  end  so  as  to  save  labour;  but  after- 
wards a large  majority  are  drawn  in  by  the 
pointed  end,  in  order  to  plug  up  the  hole  se- 
curely. 

The  fallen  petioles  of  our  native  ash-tree 
were  next  observed,  and  the  rule  with  most 
objects,  viz.,  that  a large  majority  are  dragged 
into  the  burrows  by  the  more  pointed  end,  had 
not  here  been  followed;  and  this  fact  much 
surprised  me  at  first.  These  petioles  vary  in 
length  from  5 to  8|  inches;  they  are  thick 
and  fleshy  towards  the  base,  whence  they 
taper  gently  towards  the  apex,  which  is  a little 
enlarged  and  truncated  where  the  terminal 


Chap.  II. 


THEIR  INTELLIGENCE. 


8l 


leaflet  had  been  originally  attached.  Under 
some  ash-trees  growing  in  a grass-field,  229 
petioles  were  pulled  out  of  worm  burrows  early 
in  January,  and  of  these  51.5  per  cent,  had 
been  drawn  in  by  the  base,  and  48.5  per  cent, 
by  the  apex.  This  anomaly  was  however 
readily  explained  as  soon  as  the  thick  basal 
part  was  examined;  for  in  78  out  of  103  peti- 
oles, this  part  had  been  gnawed  by  worms,  just 
above  the  horse-shoe  shaped  articulation.  In 
most  cases  there  could  be  no  mistake  about 
the  gnawing;  for  ungnawed  petioles  which 
were  examined  after  being  exposed  to  the 
weather  for  eight  additional  weeks  had  not 
become  more  disintegrated  or  decayed  near 
the  base  than  elsewhere.  It  is  thus  evident 
that  the  thick  basal  end  of  the  petiole  is 
drawn  in  not  solely  for  the  sake  of  plugging 
up  the  mouths  of  the  burrows,  but  as  food. 
Even  the  narrow  truncated  tips  of  some  few 
petioles  had  been  gnawed;  and  this  was  the 
case  in  6 out  of  37  which  were  examined  for 
this  purpose.  Worms,  after  having  drawn  in 
and  gnawed  the  basal  end,  often  push  the  peti- 
oles out  of  their  burrows;  and  then  drag  in 


82 


HABITS  OF  WORMS. 


Chap.  II. 


fresh  ones,  either  by  the  base  for  food,  or  by 
the  apex  for  plugging  up  the  mouth  more  ef- 
fectually. Thus,  out  of  37  petioles  inserted  by 
their  tips,  5 had  been  previously  drawn  in  by 
the  base,  for  this  part  had  been  gnawed. 
Again,  I collected  a handful  of  petioles  lying 
loose  on  the  ground  close  to  some  plugged-up 
burrows,  where  the  surface  was  thickly  strewed 
with  other  petioles  which  apparently  had 
never  been  touched  by  worms;  and  14  out 
of  47  (i.  e.  nearly  one-third),  after  having  had 
their  bases  gnawed  had  been  pushed  out  of 
the  burrows  and  were  now  lying  on  the 
ground.  From  these  several  facts  we  may 
conclude  that  worms  draw  in  some  petioles 
of  the  ash  by  the  base  to  serve  as  food,  and 
others  by  the  tip  to  plug  up  the  mouths 
of  their  burrows  in  the  most  efficient  man- 
ner. 

The  petioles  of  Robinia  pseudo-acacia  vary 
from  4 or  5 to  nearly  12  inches  in  length;  they 
are  thick  close  to  the  base  before  the  softer 
parts  have  rotted  off,  and  taper  much  towards 
the  upper  end.  They  are  so  flexible  that  I 
have  seen  some  few  doubled  up  and  thus 


THEIR  INTELLIGENCE. 


Chap.  II. 


83 


drawn  into  the  burrows  of  worms.  Unfor- 
tunately these  petioles  were  not  examined 
until  February,  by  which  time  the  softer  parts 
had  completely  rotted  off,  so  that  it  was  im- 
possible to  ascertain  whether  worms  had 

gnawed  the  bases,  though  this  is  in  itself 

probable.  Out  of  12 1 petioles  extracted  from 
burrows  early  in  February,  68  were  embedded 
by  the  base,  and  53  by  the  apex.  On 

February  5 all  the  petioles  which  had  been 

drawn  into  the  burrows  beneath  a Robinia, 
were  pulled  up ; and  after  an  interval  of 
eleven  days,  35  petioles  had  been  again 
dragged  in,  19  by  the  base,  and  16  by  the 
apex.  Taking  these  two  lots  together,  56  per 
cent,  were  drawn  in  by  the  base,  and  44  per 
cent,  by  the  apex.  As  all  the  softer  parts  had 
long  ago  rotted  off,  we  may  feel  sure,  espe- 
cially in  the  latter  case,  that  none  had  been 
drawn  in  as  food.  At  this  season,  therefore, 
worms  drag  these  petioles  into  their  burrows 
indifferently  by  either  end,  a slight  preference 
being  given  to  the  base.  This  latter  fact  may 
be  accounted  for  by  the  difficulty  of  plugging 
up  a burrow  with  objects  so  extremely  thin 


84 


HABITS  OF  WORMS. 


Chap.  II. 


as  are  the  upper  ends.  In  support  of  this  view, 
it  may  be  stated  that  out  of  the  16  petioles 
which  had  been  drawn  in  by  their  upper  ends, 
the  more  attenuated  terminal  portion  of  7 
had  been  previously  broken  off  by  some  ac- 
cident. 

Triangles  of  paper. — Elongated  triangles 
were  cut  out  of  moderately  stiff  writing-paper, 
which  wras  rubbed  with  raw  fat  on  both  sides, 
so  as  to  prevent  their  becoming  excessively 
limp  when  exposed  at  night  to  rain  and  dew. 
The  sides  of  all  the  triangles  were  three 
inches  in  length,  with  the  bases  of  120  one 
inch,  and  of  the  other  183  half  an  inch  in 
length.  These  latter  triangles  were  very  nar- 
row or  much  acuminated.*  As  a check  on 
the  observations  presently  to  be  given,  simi- 
lar triangles  in  a damp  state  wTere  seized  by  a 
very  narrow  pair  of  pincers  at  different  points 
and  at  all  inclinations  with  reference  to  the 
margins,  and  were  then  drawn  into  a short 
tube  of  the  diameter  of  a worm-burrow.  If 

* In  these  narrow  triangles  the  apical  angle  is  g°  34',  and  the 
basal  angles  85°  13'.  In  the  broader  triangles  the  apical  angle 
is  190  10'  and  the  basal  angles  8o°  25'. 


Chap.  II.  THEIR  INTELLIGENCE.  85 

seized  by  the  apex,  the  triangle  was  drawn 
straight  into  the  tube,  with  its  margins  in- 
folded; if  seized  at  some  little  distance  from 
the  apex,  for  instance  at  half  an  inch,  this 
much  was  doubled  back  within  the  tube.  So 
it  was  with  the  base  and  basal  angles,  though 
in  this  case  the  triangles  offered,  as  might  have 
been  expected,  much  more  resistance  to  being 
drawn  in.  If  seized  near  the  middle  the  tri- 
angle was  doubled  up,  with  the  apex  and  base 
left  sticking  out  of  the  tube.  As  the  sides  of 
the  triangles  were  three  inches  in  length,  the 
result  of  their  being  drawn  into  a tube  or  into 
a burrow  in  different  ways,  may  be  conven- 
iently divided  into  three  groups:  those  drawn 
in  by  the  apex  or  within  an  inch  of  it;  those 
drawn  in  by  the  base  or  within  an  inch  of  it; 
and  those  drawn  in  by  any  point  in  the  middle 
inch. 

In  order  to  see  how  the  triangles  would  be 
seized  by  worms,  some  in  a damp  state  were 
given  to  worms  kept  in  confinement.  They 
were  seized  in  three  different  manners  in  the 
case  of  both  the  narrow  and  broad  triangles: 
viz.,  by  the  margin;  by  one  of  the  three  angles, 


86 


HABITS  OF  WORMS. 


Chap.  II. 


which  was  often  completely  engulfed  in  their 
mouths;  and  lastly,  by  suction  applied  to  any 
part  of  the  flat  surface.  If  lines  parallel  to  the 
base  and  an  inch  apart,  are  drawn  across  a 
triangle  with  the  sides  three  inches  in  length, 
it  will  be  divided  into  three  parts  of  equal 
length.  Now  if  worms  seized  indifferently  by 
chance  any  part,  they  would  assuredly  seize 
on  the  basal  part  or  division  far  oftener  than 
on  either  of  the  two  other  divisions.  For  the 
area  of  the  basal  to  the  apical  part  is  as  5 to 
1,  so  that  the  chance  of  the  former  being  drawn 
into  a burrow  by  suction,  will  be  as  5 to  1, 
compared  with  the  apical  part.  The  base  of- 
fers two  angles  and  the  apex  only  one,  so  that 
the  former  would  have  twice  as  good  a chance 
(independently  of  the  size  of  the  angles)  of 
being  engulfed  in  a worm’s  mouth,  as  would 
the  apex.  It  should,  however,  be  stated  that 
the  apical  angle  is  not  often  seized  by  worms; 
the  margin  at  a little  distance  on  either  side 
being  preferred.  I judge  of  this  from  having 
found  in  40  out  of  46  cases  in  which  triangles 
had  been  drawn  into  furrows  by  their  apical 
ends,  that  the  tip  had  been  doubled  back 


Chap.  II.  THEIR  INTELLIGENCE.  87 

within  the  burrow  for  a length  of  between 
-gVth  of  an  inch  and  1 inch.  Lastly,  the  pro- 
portion between  the  margins  of  the  basal  and 
apical  parts  is  as  3 to  2 for  the  broad,  and  to 
2 for  the  narrow  triangles.  From  these  several 
considerations  it  might  certainly  have  been 
expected,  supposing  that  worms  seized  hold  of 
the  triangles  by  chance,  that  a considerably 
larger  proportion  would  have  been  dragged 
into  the  burrows  by  the  basal  than  by  the  apical 
part;  but  we  shall  immediately  see  how  differ- 
ent was  the  result. 

Triangles  of  the  above  specified  sizes  were 
scattered  011  the  ground  in  many  places  and 
on  many  successive  nights  near  worm-bur- 
rows, from  which  the  leaves,  petioles,  twigs, 
&c.,  with  which  they  had  been  plugged,  were 
removed.  Altogether  303  triangles  were 
drawn  by  worms  into  their  burrows:  12  others 
were  drawn  in  by  both  ends,  but  as  it  was  im- 
possible to  judge  by  which  end  they  had  been 
first  seized,  these  are  excluded.  Of  the  303, 
62  per  cent,  had  been  drawn  in  by  the  apex 
(using  this  term  for  all  drawn  in  by  the  apical 
part,  one  inch  in  length);  15  per  cent,  by  the 


88 


HABITS  OF  WORMS. 


Chap.  II. 


middle;  and  23  per  cent,  by  the  basal  part.  If 
they  had  been  drawn  indifferently  by  any 
point,  the  proportion  for  the  apical,  middle  and 
basal  parts  would  have  been  33.3  per  cent,  for 
each;  but,  as  we  have  just  seen,  it  might  have 
been  expected  that  a much  larger  proportion 
would  have  been  drawn  in  by  the  basal  than 
by  any  other  part.  As  the  case  stands,  nearly 
three  times  as  many  were  drawn  in  by  the  apex 
as  by  the  base.  If  we  consider  the  broad  tri- 
angles by  themselves,  59  per  cent,  were  drawn 
in  by  the  apex,  25  per  cent,  by  the  middle,  and 
16  per  cent,  by  the  base.  Of  the  narrow  tri- 
angles, 65  per  cent,  were  drawn  in  by  the 
apex,  14  per  cent,  by  the  middle,  and  21  per 
cent,  by  the  base;  so  that  here  those  drawn  in 
by  the  apex  were  more  than  3 times  as  many 
as  those  drawn  in  by  the  base.  We  may  there- 
fore conclude  that  the  manner  in  which  the 
triangles  are  drawn  into  the  burrows  is  not  a 
matter  of  chance. 

In  eight  cases,  two  triangles  had  been 
drawn  into  the  same  burrow,  and  in  seven  of 
these  cases,  one  had  been  drawn  in  by  the 
apex  and  the  other  by  the  base.  This  again 


Chap.  II. 


THEIR  INTELLIGENCE. 


89 


indicates  that  the  result  is  not  determined  by 
chance.  Worms  appear  sometimes  to  revolve 
in  the  act  of  drawing  in  the  triangles,  for  five 
out  of  the  whole  lot  had  been  wound  into  an 
irregular  spire  round  the  inside  of  the  burrow. 
Worms  kept  in  a warm  room  drew  63  tri- 
angles into  their  burrows;  but,  as  in  the  case 
of  the  pine-leaves,  they  worked  in  a rather 
careless  manner,  for  only  44  per  cent,  were 
drawn  in  by  the  apex,  22  per  cent,  by  the  mid- 
dle, and  33  per  cent,  by  the  base.  In  five 
cases,  two  triangles  were  drawn  into  the  same 
burrow. 

It  may  be  suggested  with  much  apparent 
probability  that  so  large  a proportion  of  the 
triangles  were  drawn  in  by  the  apex,  not  from 
the  worms  having  selected  this  end  as  the  most 
convenient  for  the  purpose,  but  from  having 
first  tried  in  other  ways  and  failed.  This  no- 
tion was  countenanced  by  the  manner  in  which 
worms  in  confinement  were  seen  to  drag  about 
and  drop  the  triangles;  but  then  they  were 
working  carelessly.  I did  not  at  first  perceive 
the  importance  of  this  subject,  but  merely  no- 
ticed that  the  bases  of  those  triangles  which 
7 


90 


HABITS  OF  WORMS. 


Chap.  II. 


had  been  drawn  in  by  the  apex,  were  generally 
clean  and  not  crumpled.  The  subject  was 
afterwards  attended  to  carefully.  In  the  first 
place  several  triangles  which  had  been  drawn 
in  by  the  basal  angles,  or  by  the  base,  or  a 
little  above  the  base,  and  which  were  thus 
much  crumpled  and  dirtied,  were  left  for  some 
hours  in  water  and  were  then  well  shaken 
while  immersed;  but  neither  the  dirt  nor  the 
creases  were  thus  removed.  Only  slight 
creases  could  be  obliterated,  even  by  pulling 
the  wet  triangles  several  times  through  my 
fingers.  Owing  to  the  slime  from  the  worms’ 
bodies,  the  dirt  was  not  easily  washed  off.  We 
may  therefore  conclude  that  if  a triangle,  be- 
fore being  dragged  in  by  the  apex,  had  been 
dragged  into  a burrow  by  its  base  with  even 
a slight  degree  of  force,  the  basal  part  would 
long  retain  its  creases  and  remain  dirty.  The 
condition  of  89  triangles  (65  narrow  and  24 
broad  ones),  which  had  been  drawn  in  by  the 
apex,  was  observed;  and  the  bases  of  only  7 
of  them  were  at  all  creased,  being  at  the  same 
time  generally  dirty.  Of  the  82  uncreased  tri- 
angles, 14  were  dirty  at  the  base;  but  it  does 


THEIR  INTELLIGENCE. 


Chap.  II. 


9* 


not  follow  from  this  fact  that  these  had  first 
been  dragged  towards  the  burrows  by  their 
bases;  for  the  worms  sometimes  covered  large 
portions  of  the  triangles  with  slime,  and  these 
when  dragged  by  the  apex  over  the  ground 
would  be  dirtied;  and  during  rainy  weather, 
the  triangles  were  often  dirtied  over  one  whole 
side  or  over  both  sides.  If  the  worms  had 
dragged  the  triangles  to  the  mouths  of  their 
burrows  by  their  bases,  as  often  as  by  their 
apices,  and  had  then  perceived,  without  actual- 
ly trying  to  draw  them  into  the  burrow,  that 
the  broader  end  was  not  well  adapted  for  this 
purpose — even  in  this  case  a large  proportion 
would  probably  have  had  their  basal  ends  dir- 
tied. We  may  therefore  infer — improbable  as 
is  the  inference — that  worms  are  able  by  some 
means  to  judge  which  is  the  best  end  by  which 
to  draw  triangles  of  paper  into  their  bur- 
rows. 

The  percentage  results  of  the  foregoing  ob- 
servations on  the  manner  in  which  worms 
draw  various  kinds  of  objects  into  the  mouths 
of  their  burrows  may  be  abridged  as  fol- 
lows : — - 


92 


HABITS  OF  WORMS. 


Chap.  II. 


Nature  of  Object. 

Drawn 
into  the 
bur- 
rows, by 
or  near 
the 

Drawn 
in,  by  or 
near  the 
middle. 

Drawn 
in,  by  or 
near  the 
base. 

apex. 

Leaves  of  various  kinds 

8o 

II 

9 

of  the  Lime,  basal  margin  of  blade 

broad,  apex  acuminated  . 

79 

17 

4 

— of  a Laburnum,  basal  part  of  blade 

as  narrow  as,  or  sometimes  lit- 
tle narrower  than  the  apical 
part  . 

63 

10 

27 

of  the  Rhododendron,  basal  part 

of  blade  often  narrower  than 
the  apical  part 

34 

66 

of  Pine-trees,  consisting  of  two 

needles  arising  from  a common 
base  . 

100 

Petioles  of  a Clematis,  somewhat  pointed 
at  the  apex,  and  blunt  at  the 
base  . 

76 

24 

of  the  Ash,  the  thick  basal  end 

often  drawn  in  to  serve  as  food 

48.5 

51.5 

of  Robinia,  extremely  thin,  espe- 

dally  towards  the  apex,  so  as 
to  be  ill-fitted  for  plugging  up 
the  burrows  .... 

44 

56 

Triangles  of  paper,  of  the  two  sizes 

62 

15 

23 

of  the  broad  ones  alone  . 

59 

25 

16 

of  the  narrow  ones  alone 

65 

14 

21 

If  we  consider  these  several  cases,  we  can 
hardly  escape  from  the  conclusion  that  worms 
show  some  degree  of  intelligence  in  their  man- 
ner of  plugging  up  their  burrows.  Each  par- 
ticular object  is  seized  in  too  uniform  a man- 

1 


Chap.  II. 


THEIR  INTELLIGENCE. 


93 


ner,  and  from  causes  which  we  can  generally 
understand,  for  the  result  to  be  attributed  to 
mere  chance.  That  every  object  has  not  been 
drawn  in  by  its  pointed  end,  may  be  accounted 
for  by  labour  having  been  saved  through  some 
being  inserted  by  their  broader  or  thicker  ends. 
No  doubt  Xvorms  are  led  by  instinct  to  plug 
up  their  burrows;  and  it  might  have  been  ex- 
pected that  they  would  have  been  led  by  in- 
stinct how  best  to  act  in  each  particular  case, 
independently  of  intelligence.  We  see  how 
difficult  it  is  to  judge  whether  intelligence 
comes  into  play,  for  even  plants  might  some- 
times be  thought  to  be  thus  directed;  for  in- 
stance when  displaced  leaves  re-direct  their 
upper  surfaces  towards  the  light  by  extremely 
complicated  movements  and  by  the  shortest 
course.  With  animals,  actions  appearing  due 
to  intelligence  may  be  performed  through  in- 
herited habit  without  any  intelligence,  al- 
though aboriginally  thus  acquired.  Or  the 
habit  may  have  been  acquired  through  the 
preservation  and  inheritance  of  beneficial  vari- 
ations of  some  other  habit;  and  in  this  case 
the  new  habit  will  have  been  acquired  inde- 


94 


HABITS  OF  WORMS. 


Chap.  II. 


pendently  of  intelligence  throughout  the  whole 
course  of  its  development.  There  is  no  a priori 
improbability  in  worms  having  acquired  spe- 
cial instincts  through  either  of  these  two  latter 
means.  Nevertheless  it  is  incredible  that  in- 
stincts should  hqve  been  developed  in  refer- 
ence to  objects/such  as  the  leaves  or  petioles 
of  foreign  plahts,  wholly  unknown  to  the  pro- 
genitors oj/the  worms  which  act  in  the  de- 
scribed manner.  Nor  are  their  actions  so  un- 
varying or  inevitable  as  are  most  true  in- 
stincts. 

As  worms  are  not  guided  by  special  in- 
stincts in  each  particular  case,  though  possess- 
ing a general  instinct  to  plug  up  their  bur- 
rows, and  as  chance  is  excluded,  the  next  most 
probable  conclusion  seems  to  be  that  they  try 
in  many  different  ways  to  draw  in  objects,  and 
at  last  succeed  in  some  one  way.  But  it  is  sur- 
prising that  an  animal  so  low  in  the  scale  as  a 
worm  should  have  the  capacity  for  acting  in 
this  manner,  as  many  higher  animals  have  no 
such  capacity.  For  instance,  ants  may  be 
seen  vainly  trying  to  drag  an  object  transverse- 
ly to  their  course,  which  could  be  easily  drawn 


Chap.  II. 


THEIR  INTELLIGENCE. 


95 


longitudinally;  though  after  a time  they  gen- 
erally act  in  a wiser  manner.  M.  Fabre  states  * 
that  a Sphex — an  insect  belonging  to  the  same 
highly-endowed  order  with  ants — stocks  its 
nest  with  paralysed  grasshoppers,  which  are 
invariably  dragged  into  the  burrow  by  their 
antennae.  When  these  were  cut  off  close  to 
the  head,  the  Sphex  seized  the  palpi;  but  when 
these  were  likewise  cut  off,  the  attempt  to  drag 
its  prey  into  the  burrow  was  given  up  in  de- 
spair. The  Sphex  had  not  intelligence  enough 
to  seize  one  of  the  six  legs  or  the  ovipositor  of 
the  grasshopper,  which,  as  M.  Fabre  remarks, 
would  have  served  equally  well.  So  again,  if 
the  paralysed  prey  with  an  egg  attached  to  it 
be  taken  out  of  the  cell,  the  Sphex  after  enter- 
ing and  finding  the  cell  empty,  nevertheless 
closes  it  up  in  the  usual  elaborate  manner. 
Bees  will  try  to  escape  and  go  on  buzzing  for 
hours  on  a window,  one  half  of  which  has  been 
left  open.  Even  a pike  continued  during  three 
months  to  dash  and  bruise  itself  against  the 
glass  sides  of  an  aquarium,  in  the  vain  attempt 

* See  his  interesting  work,  “ Souvenirs  entomologiques,” 
1879,  pp.  168-177. 


g6  HABITS  OF  WORMS.  Chap.  IL 

to  seize  minnows  on  the  opposite  side.*  A 
cobra-snake  was  seen  by  Mr.  Layard  j-  to  act 
much  more  wisely  than  either  the  pike  or  the 
Sphex;  it  had  swallowed  a toad  lying  within 
a hole,  and  could  not  withdraw  its  head;  the 
toad  was  disgorged,  and  began  to  crawl  away; 
it  was  again  swallowed  and  again  disgorged; 
and  now  the  snake  had  learnt  by  experience, 
for  it  seized  the  toad  by  one  of  its  legs  and 
drew  it  out  of  the  hole.  The  instincts  of  even 
the  higher  animals  are  often  followed  in  a 
senseless  or  purposeless  manner:  the  weaver- 
bird  will  perseveringly  wind  threads  through 
the  bars  of  its  cage,  as  if  building  a nest:  a 
squirrel  will  pat  nuts  on  a wooden  floor,  as  if 
he  had  just  buried  them  in  the  ground:  a 
beaver  will  cut  up  logs  of  wood  and  drag  them 
about,  though  there  is  no  water  to  dam  up; 
and  so  in  many  other  cases. 

Mr.  Romanes,  who  has  specially  studied 
the  minds  of  animals,  believes  that  we  can 
safely  infer  intelligence, -orriy-wfaTr-we^see  an 

* Mobius,  “ Die  Bewegungen  der  Thiere,”  &c.,  1873,  p. 
in. 

f ‘‘Annals  and  Mag.  of  N.  History,”  series  ii.  vol.  ix.  1852, 
P-  333. 


Chap.  II. 


THEIR  INTELLIGENCE. 


97 


By  this  test  the  cobra  showed  some  intelli- 
gence; but  this  would  have  been  much  plainer 
if  on  a second  occasion  he  had  drawn  a toad 
out  of  a hole  by  its  leg.  The  Sphex  failed  sig- 
nally in  this  respect.  Now  if  worms  try  to 
drag  objects  into  their  burrows  first  in  one 
way  and  then  in  another,  until  they  at  last  suc- 
ceed, they  profit,  at  least  in  each  particular 
instance,  by  experience. 

But  evidence  has  been  advanced  showing 
that  worms  do  not  habitually  try  to  draw 
objects  into  their  burrows  in  many  different 
ways.  Thus  half-decayed  lime-leaves  from 
their  flexibility  could  have  been  drawn  in  by 
their  middle  or  basal  parts,  and  were  thus 
drawn  into  the  burrows  in  considerable  num- 
bers; yet  a large  majority  were  drawn  in  by 
or  near  the  apex.  The  petioles  of  the  Clematis 
could  certainly  have  been  drawn  in  with  equal 
ease  by  the  base  and  apex;  yet  three  times 
and  in  certain  cases  five  times  as  many  were 
drawn  in  by  the  a^x  as  by  the  base.  It  might 
have  been  thought  that  the  foot-stalks  of 
leaves  would  have  tempted  the  worms  as  a con- 


98 


HABITS  OF  WORMS. 


Chap.  II. 


venient  handle;  yet  they  are  not  largely  used, 
except  when  the  base  of  the  blade  is  narrower 
than  the  apex.  A large  number  of  the  petioles 
of  the  ash  are  drawn  in  by  the"  base;  but  this 
part  serves  the  worms  as  food.  In  the  case  of 
pine-leaves  worms  plainly  show  that  they  at 
least  do  not  seize  the  leaf  by  chance;  but  their 
choice  does  not  appear  to  be  determined  by 
the  divergence  of  the  two  needles,  and  the 
consequent  advantage  or  necessity  of  drawing 
them  into  their  burrows  by  the  base.  With 
respect  to  the  triangles  of  paper,  those  which 
had  been  drawn  in  by  the  apex  rarely  had 
their  bases  creased  or  dirty;  and  this  shows 
that  the  worms  had  not  often  first  tried  to 
drag  them  in  by  this  end. 

If  worms  are  able  to  judge,  either  before 
drawing  or  after  having  drawn  an  object  close 
to  the  mouths  of  their  burrows,  how  best  to 
drag  it  in,  they  must  acquire  some  notion  of 
its  general  shape.  This  they  probably  acquire 
by  touching  it  in  many  places  with  the  an- 
terior extremity  of  their  bodies,  which  serves 
as  a tactile  organ.  It  may  be  well  to  remem- 
ber how  perfect  the  sense  of  touch  becomes 


Chap.  II. 


THEIR  INTELLIGENCE. 


99 


in  a man  when  born  blind  and  deaf,  as  are 
worms.  If  worms  have  the  power  of  acquiring 
some  notion,  however  rude,  of  the  shape  of  an 
object  and  of  their  burrows,  as  seems  to  be 
the  case,  they  deserve  to  be  called  intelligent; 
for  they  then  act  in  nearly  the  same  manner  as 
would  a man  under  similar  circumstances.  J 
To  sum  up,  as  chance  does  not  determine 
the  manner  in  which  objects  are  drawn  into 
the  burrows,  and  as  the  existence  of  special- 
ized instincts  for  each  particular  case  cannot 
be  admitted,  the  first  and  most  natural  sup- 
position is  that  worms  try  all  methods  until 
they  at  last  succeed;  but  many  appearances 
are  opposed  to  such  a supposition.  One  al- 
ternative alone  is  left,  namely,  that  worms, 
although  standing  low  in  tbe  scale  of  organiza- 
tion, possess  some  degree  of  intelligence.  This 
will  strike  every  one  as  very  improbable;  but 
it  may  be  doubted  whether  we  know  enough 
about  the  nervous  system  of  the  lower  animals 
to  justify  our  natural  distrust  of  such  a con- 
clusion. With  respect  to  the  small  size  of  the 
cerebral  ganglia,  we  should  remember  what 
a mass  of  inherited  knowledge,  with  some 


IOO 


HABITS  OF  WORMS. 


Chap.  II. 


power  of  adapting  means  to  an  end,  is  crowded 
into  the  minute  brain  of  a worker-ant. 

Means  by  which  worms  excavate  their  bur- 
rows.— This  is  effected  in  two  ways;  by  push- 
ing  away  the  earth  on  all  sides,  and  by^swalc 
lov^gjt^  In  tK~e  tormer  caseT~the  worm  inserts 
the  stretched  out  and  attenuated  anterior  ex- 
tremity of  its  body  into  any  little  crevice,  or 
hole  ; and  then,  as  Perrier  remarks,*  the 
pharynx  is  pushed  forwards  into  this  part, 
which  consequently  swells  and  pushes  away 
the  earth  on  all  sides.  The  anterior  extremity 
thus  serves  as  a wedge.  It  also  serves,  as  we 
have  before  seen,  for  prehension  and  suction, 
and  as  a tactile  organ.  A worm  was  placed  on 
loose  mould,  and  it  buried  itself  in  between 
two  and  three  minutes.  On  another  occasion 
four  worms  disappeared  in  1 5 minutes  between 
the  sides  of  the  pot  and  the  earth,  which  had 
been  moderately  pressed  down.  On  a third 
occasion  three  large  worms  and  a small  one 
were  placed  on  loose  mould  well  mixed  with 
fine  sand  and  firmly  pressed  down,  and  they 
all  disappeared,  except  the  tail  of  one,  in  35 

* “ Archives  de  Zoolog.  exper.,”  tom.  iii.  1874,  p.  405. 


Chap.  II.  EXCAVATION  OF  THEIR  BURROWS,  iqi 


minutes.  On  a fourth  occasion  six  large 
worms  were  placed  on  argillaceous  mud  mixed 
with  sand  firmly  pressed  down,  and  they  dis- 
appeared, except  the  extreme  tips  of  the  tails 
of  two  of  them,  in  40  minutes.  In  none  of 
these  cases,  did  the  worms  swallow,  as  far  as 
could  be  seen,  any  earth.  They  generally  en- 
tered the  ground  close  to  the  sides  of  the  pot. 

A pot  was  next  filled  with  very  fine  ferru- 
ginous sand,  which  was  pressed  down,  well 
watered,  and  thus  rendered  extremely  com- 
pact. A large  worm  left  on  the  surface  did 
not  succeed  in  penetrating  it  for  some  hours, 
and  did  not  bury  itself  completely  until  25 
hrs.  40  min.  had  elapsed.  This  was  effected 
by  the  sand  being  swallowed,  as  was  evident 
by  the  large  quantity  ejected  from  the  vent, 
long  before  the  whole  body  had  disappeared. 
Castings  of  a similar  nature  continued  to  be 
ejected  from  the  burrow  during  the  whole  of 
the  following  day. 

As  doubts  have  been  expressed  by  some 
writers  whether  worms  ever  swallow  earth 
solely  for  the  sake  of  making  their  burrows, 
some  additional  cases  may  be  given.  A mass 


102 


HABITS  OF  WORMS. 


Chap.  II. 


of  fine  reddish  sand,  23  inches  in  thickness, 
left  on  the  ground  for  nearly  two  years,  had 
been  penetrated  in  many  places  by  worms; 
and  their  castings  consisted  partly  of  the  red- 
dish sand  and  partly  of  black  earth  brought  up 
from  beneath  the  mass.  This  sand  had  been 
dug  up  from  a considerable  depth,  and  was 
of  so  poor  a nature  that  weeds  could  not  grow 
on  it.  It  is  therefore  highly  improbable  that 
it  should  have  been  swallowed  by  the  worms 
as  food.  Again  in  a field  near  my  house  the 
castings  frequently  consist  of  almost  pure 
chalk,  which  lies  at  only  a little  depth  beneath 
the  surface;  and  here  again  it  is  very  improb- 
able that  the  chalk  should  have  been  swallowed 
for  the  sake  of  the  very  little  organic  matter 
which  could  have  percolated  into  it  from  the 
poor  overlying  pasture.  Lastly,  a casting 
thrown  up  through  the  concrete  and  decayed 
mortar  between  the  tiles,  with  which  the  now 
ruined  aisle  of  Beaulieu  Abbey  had  formerly 
been  paved,  was  washed,  so  that  the  coarser 
matter-  alone  was  left.  This  consisted  of  grains 
of  quartz,  micaceous  slate,  other  rocks,  and. 
bricks  or  tiles,  many  of  them  from  to  ^ 


Chap.  II.  EARTH  SWALLOWED  AS  FOOD. 


103 


inch  in  diameter.  No  one  will  suppose  that 
these  grains  were  swallowed  as  food,  yet  they 
formed  more  than  half  of  the  casting,  for  they 
weighed  19  grains,  the  whole  casting  having 
weighed  33  grains.  Whenever  a worm  bur- 
rows to  a depth  of  some  feet  in  undisturbed 
compact  ground,  it  must  form  its  passage  by 
swallowing  the  earth;  for  it  is  incredible  that 
the  ground  could  yield  on  all  sides  to  the  pres- 
sure of  the  pharynx  when  pushed  forwards 
within  the  worm’s  body. 

That  worms  swallow  a larger  quantity  of 
earth  for  the  sake  of  extracting  any  nutritious 
matter  which  it  may  contain  than  for  making 
their  burrows,  appears  to  me  certain.  But 
as  this  old  belief  has  been  doubted  by  so  high 
an  authority  as  Claparede,  evidence  in  its 
favour  must  be  given  in  some  detail.  There 
is  no  a priori  improbability  in  such  a belief, 
for  besides  other  annelids,  especially  the  Areni- 
cola  marina , which  throws  up  such  a profusion 
of  castings  on  our  tidal  sands,  and  which  it  is 
believed  thus  subsists,  there  are  animals  be- 
longing to  the  most  distinct  classes,  which  do 
not  burrow,  but  habitually  swallow  large 


104 


HABITS  OF  WORMS. 


Chap.  II. 


quantities  of  sand;  namely  the  molluscan  On- 
chidium  and  many  Echinoderms.* 

If  earth  were  swallowed  only  when  worms 
deepened  their  burrows  or  made  new  ones, 
castings  would  be  thrown  up  only  occasion- 
ally; but  in  many  places  fresh  castings  may 
be  seen  every  morning,  and  the  amount  of 
earth  ejected  from  the  same  burrow  on  suc- 
cessive days  is  large.  Yet  worms  do  not  bur- 
row to  a great  depth,  except  when  the  weath- 
er is  very  dry  or  intensely  cold.  On  my  lawn 
the  black  vegetable  mould  is  only  about  5 
inches  in  thickness,  and  overlies  light-coloured 
or  reddish  clayey  soil:  now  when  castings  are 
thrown  up  in  the  greatest  profusion,  only  a 
small  proportion  are  light  coloured,  and  it  is 
incredible  th^dy^wcHmrs-Ahmdd^TLail^  make 
fresh  burrows  in  every  direction  in  the  thin 
superficial  layer  of  dark-coloured  humus,  un- 
less they  obtained  fflitriment  of  some  kindfrOMi 

it I have  obseWed  a strictly  analogous  case 

in  a field  near  my  house  where  bright  red  clay 
lay  close  beneath  the  surface.  Again  on  one 

* I state  this  on  the  authority  of  Semper,  “ Reisen  im  Archi- 
pel  der  Philippinen,”  Th.  ii.  1877,  p.  30. 


Chap.  II.  EARTH  SWALLOWED  AS  FOOD. 


105 


part  of  the  Downs  near  Winchester  the  vege- 
table mould  overlying  the  chalk  was  found  to 
be  only  from  3 to  4 inches  in  thickness;  and 
the  many  castings  here  ejected  were  as  black 
as  ink  and  did  not  effervesce  with  acids;  so 
that  the  worms  must  have  confined  themselves 
to  this  thin  superficial  layer  of  mould,  of  which 
large  quantities  were  daily  swallowed.  In  an- 
other place  at  no  great  distance  the  castings 
were  white;  and  why  the  worms  should  have 
burrowed  into  the  chalk  in  some  places  and 
not  in  others,  I am  unable  to  conjecture. 

Two  great  piles  of  leaves  had  been  left  to 
decay  in  my  grounds,  and  months  after  their 
removal,  the  bare  surface,  several  yards  in 
diameter,  was  so  thickly  covered  during  sev- 
eral months  with  castings  that  they  formed  an 
almost  continuous  layer;  and  the  large  num- 
ber of  worms  which  lived  here  must  have  sub- 
sisted during  these  months  on  nutritious  mat- 
ter contained  in  the  black  earth. 

The  lowest  layer  from  another  pile  of  de- 
cayed leaves  mixed  with  some  earth  was  ex- 
amined under  a high  power,  and  the  number 

of  spores  of  various  shapes  and  sizes  which 

8 


io6 


HABITS  OF  WORMS. 


Chap.  II. 


it  contained  was  astonishingly  great;  and  these 
crushed  in  the  gizzards  of  worms  may  largely 
aid  in  supporting  them.  Whenever  castings 
are  thrown  up  in  the  greatest  number,  few  or 
no  leaves  are  drawn  into  the  burrows;  for  in- 
stance the  turf  along  a hedge-row,  about  200 
yards  in  length,  was  daily  observed  in  the  au- 
tumn during  several  weeks,  and  every  morn- 
ing many  fresh  castings  were  seen;  but  not  a 
single  leaf  was  drawn  into  these  burrows. 
These  castings  from  their  blackness  and  from 
the  nature  of  the  subsoil  could  not  have  been 
brought  up  from  a greater  depth  than  6 or  8 
inches.  On  what  could  these  worms  have  sub- 
sisted during  this  whole  time,  if  not  on  matter 
contained  in  the  black  earth?  On  the  other 
hand,  whenever  a large  number  of  leaves  are 
drawn  into  the  burrows,  the  worms  seem  to 
subsist  chiefly  on  them,  for  few  earth-castings 
are  then  ejected  on  the  surface.  This  differ- 
ence in  the  behaviour  of  worms  at  different 
times,  perhaps  explains  a statement  by  Clapa- 
rede,  namely,  that  triturated  leaves  and  earth 
are  always  found  in  distinct  parts  of  their  in- 
testines. 


Chap.  II.  EARTH  SWALLOWED  AS  FOOD. 


107 


Worms  sometimes  abound  in  places  where 
they  can  rarely  or  never  obtain  dead  or  living 
leaves;  for  instance,  beneath  the  pavement  in 
well-swept  courtyards,  into  which  leaves  are 
only  occasionally  blown.  My  son  Horace  ex- 
amined a house,  one  corner  of  which  had  sub- 
sided; and  he  found  here  in  the  cellar,  which 
was  extremely  damp,  many  small  worm-cast- 
ings thrown  up  between  the  stones  with  which 
the  cellar  was  paved;  and  in  this  case  it  is  im- 
probable that  the  worms  could  ever  have  ob- 
tained leaves. 

But  the  best  evidence,  known  to  me,  of 
worms  subsisting  for  at  least  considerable  pe- 
riods of  time  solely  on  the  organic  matter  con^ 
tained  in  earth,  is  afforded  by  some  facts  com- 
municated to  me  by  Dr.  King.  Near  Nice 
large  castings  abound  in  extraordinary  num- 
bers, so  that  5 or  6 were  often  found  within 
the  space  of  a square  foot.  They  consist  of 
fine,  pale-coloured  earth,  containing  calcare- 
ous matter,  which  after  having  passed  through 
the  bodies  of  worms  and  being  dried,  coheres 
with  considerable  force.  I have  reason  to  be- 
lieve that  these  castings  had  been  formed  by 


io8 


HABITS  OF  WORMS. 


Chap.  II. 


species  of  Perichseta,  which  have  been  natural- 
ised here  from  the  East.*  They  rise  like  tow- 
ers (see  Fig.  2),  with  their  summits  often  a little 
broader  than  their  bases,  sometimes  to  a height 
of  above  3 and  often  to  a height  of  2%  inches. 
The  tallest  of  those  which  were  measured  was 
3.3  inches  in  height  and  1 in  diameter.  A 
small  cylindrical  passage  runs  up  the  centre  of 
each  tower,  through  which  the  worm  ascends 
to  eject  the  earth  which  it  has  swallowed,  and 
thus  to  add  to  its  height.  A structure  of  this 
kind  would  not  allow  leaves  being  easily 
dragged  from  the  surrounding  ground  into  the 
burrows;  and  Dr.  King,  who  looked  carefully, 
never  saw  even  a fragment  of  a leaf  thus  drawn 
in.  Nor  could  any  trace  be  discovered  of  the 

* Dr.  King  gave  me  some  worms  collected  near  Nice,  which, 
as  he  believes,  had  constructed  these  castings.  They  were  sent 
to  M.  Perrier,  who  with  great  kindness  examined  and  named  them 
for  me : they  consisted  of  Perichceta  affinisy  a native  of  Cochin 
China  and  of  the  Philippines  ; P.  Luzonica , a native  of  Luzon 
in  the  Philippines  ; and  P.  Houlleti , which  lives  near  Calcutta. 
M.  Perrier  informs  me  that  species  of  Perichaeta  have  been 
naturalized  in  the  gardens  near  Montpellier  and  in  Algiers. 
Before  I had  any  reason  to  suspect  that  the  tower-like  castings 
from  Nice  had  been  formed  by  worms  not  endemic  in  the  coun- 
try, I was  greatly  surprised  to  see  how  closely  they  resembled 
castings  sent  to  me  from  near  Calcutta,  where  it  is  known  that 
species  of  Perichaeta  abound. 


Chap.  II.  EARTH  SWALLOWED  AS  FOOD.  109 

worms  having  crawled  down  the  exterior  sur- 
faces of  the  towers  in  search  of  leaves;  and  had 
they  done  so,  tracks  would  almost  certainly 


Fig.  2. — Tower-like  casting  from  near  Nice,  constructed  of 
earth,  voided  probably  by  a species  of  Perichaeta  ; of  natu- 
ral size,  copied  from  a photograph. 

have  been  left  on  the  upper  part  whilst  it  re- 
mained soft.  It  does  not,  however,  follow 
that  these  worms  do  not  draw  leaves  into  their 
burrows  during  some  other  season  of  the  year, 


I IO 


HABITS  OF  WORMS. 


Chap.  II. 


at  which  time  they  would  not  build  up  their 
towers. 


From  the  several  foregong  cases,  it  a 
hardly  be  doubted  that  worms  swallow  eart 


not  only  for  the  sake  of  making  their  burrow 
but  for  obtaining  food.  Hensen,  however, 
concludes  from  his  analyses  of  humus  that 
worms  probably  could  not  live  on  ordinary 
vegetable  mould,  though  he  admits  that  they 
might  be  nourished  to  some  extent  by  leaf- 
mould.*  But  we  have  seen  that  worms  eager- 
ly devour  raw  meat,  fat,  and  dead  worms;  and 
ordinary  mould  can  hardly  fail  to  obtain  many 
ova,  larvae,  and  small  living  or  dead  creatures, 
spores  of  cryptogamic  plants,  and  micrococci, 
such  as  those  which  give  rise  to  saltpetre. 
These  various  organisms,  together  with  some 
cellulose  from  any  leaves  and  roots  not  utterly 
decayed,  might  well  account  for  such  large 
quantities  of  mould  being  swallowed  by 
worms.  It  may  be  worth  while  here  to  recall 
the  fact  that  certain  species  of  Utricularia, 
which  grow  in  damp  places  in  the  tropics,  pos- 

* “ Zeitschrift  fur  wissenschaft.  Zoolog.,”  B.  xxviii,  1877, 

p.  364. 


Chap.  II.  DEPTH  OF  THEIR  BURROWS. 


Ill 


sess  bladders  beautifully  constructed  for  catch- 
ing minute  subterranean  animals;  and  these 
traps  would  not  have  been  developed  unless 
many  small  animals  inhabited  such  soil. 

The  depth  to  which  worms  penetrate,  and  the 
construction  of  their  burrows . — Although  worms 
usually  live  near  the  surface,  yet  they  burrow 
to  a considerable  depth  during  long-continued 
dry  weather  and  severe  cold.  In  Scandinavia, 
according  to  Eisen,  and  in  Scotland,  according 
to  Mr.  Lindsay  Carnagie,  the  burrows  run 
down  to  a depth  of  from  7 to  8 feet;  in  North 
Germany,  according  to  Hoffmeister,  from  6 to 
8 feet,  but  Hensen  says,  from  3 to  6 feet.  This 
latter  observer  has  seen  worms  frozen  at  a 
depth  of  1^  feet  beneath  the  surface.  I have 
not  myself  had  many  opportunities  for  obser- 
vation, but  I have  often  met  with  worms  at 
depths  of  3 to  4 feet.  In  a bed  of  fine  sand 
overlying  the  chalk,  which  had  never  been  dis- 
turbed, a worm  was  cut  into  two  at  55  inches, 
and  another  was  found  here  in  December  at 
the  bottom  of  its  burrow,  at  61  inches  beneath 
the  surface.  Lastly,  in  earth  near  an  old  Ro- 
man Villa,  which  had  not  been  disturbed  for 


1 12 


HABITS  OF  WORMS. 


Chap.  II. 


many  centuries,  a worm  was  met  with  at  a 
depth  of  66  inches;  and  this  was  in  the  middle 
of  August. 

The  burrows  run  down  perpendicularly,  or 
more  commonly  a little  obliquely.  They  are 
said  sometimes  to  branch,  but  as  far  as  I have 
seen  this  does  not  occur,  except  in  recently 
dug  ground  and  near  the  surface.  They  are 
generally,  or  as  I believe  invariably,  lined  with 
a thin  layer  of  fine,  dark-coloured  earth  voided 
by  the  worms;  so  that  they  must  at  first  be 
made  a little  wider  than  their  ultimate  diame- 
ter. I have  seen  several  burrows  in  undis- 
turbed sand  thus  lined  at  a depth  of  4 ft.  6 in.; 
and  others  close  to  the  surface  thus  lined 
in  recently  dug  ground.  The  walls  of  fresh 
burrows  are  often  dotted  with  little  globular 
pellets  of  voided  earth,  still  soft  and  viscid; 
and  these,  as  it  appears,  are  spread  out  on  all 
sides  by  the  worm  as  it  travels  up  or  down  its 
burrow.  The  lining  thus  formed  becomes 
very  compact  and  smooth  when  nearly  dry, 
and  closely  fits  the  worm’s  body.  The  minute 
reflexed  bristles  which  project  in  rows  on  all 
sides  from  the  body,  thus  have  excellent  points 


Ch.  II.  CONSTRUCTION  OF  THEIR  BURROWS.  113 

of  support;  and  the  burrow  is  rendered  well 
adapted  for  the  rapid  movement  of  the  animal. 
The  lining  appears  also  to  strengthen  the 
walls,  and  perhaps  saves  the  worm's  body  from 
being  scratched.  I think  so  because  several 
burrows  which  passed  through  a layer  of  sifted 
coal-cinders,  spread  over  turf  to  a thickness 
of  1^  inch,  had  been  thus  lined  to  an  unusual 
thickness.  In  this  case  the  worms,  judging 
from  the  castings,  had  pushed  the  cinders 
away  on  all  sides  and  had  not  swallowed  any  of 
them.  In  another  place,  burrows  similarly 
lined,  passed  through  a layer  of  coarse  coal- 
cinders,  3^  inches  in  thickness.  We  thus  see 
that  the  burrows  are  not  mere  excavations, 
but  may  rather  be  compared  with  tunnels  lined 
with  cement. 

The  mouths  of  the  burrow  are  in  addition 
often  lined  with  leaves;  and  this  is  an  instinct 
distinct  from  that  of  plugging  them  up,  and 
does  not  appear  to  have  been  hitherto  no- 
ticed. Many  leaves  of  the  Scotch-fir  or  pine 
{Finns  sylvestris)  were  given  to  worms  kept  in 
confinement  in  two  pots;  and  when  after  sev- 
eral weeks  the  earth  was  carefully  broken  up, 


1 14  HABITS  OF  WORMS.  Chap.  II. 

the  upper  parts  of  three  oblique  burrows  were 
found  surrounded  for  lengths  of  7,  4,  and  3^ 
inches  with  pine-leaves,  together  with  frag- 
ments of  other  leaves  which  had  been  given  the 
worms  as  food.  Glass  beads  and  bits  of  tile, 
which  had  been  strewed  on  the  surface  of  the 
soil,  were  stuck  into  the  interstices  between 
the  pine-leaves;  and  these  interstices  were 
likewise  plastered  with  the  viscid  castings  void- 
ed by  the  worms.  The  structures  thus  formed 
cohered  so  well,  that  I succeeded  in  removing 
one  with  only  a little  earth  adhering  to  it.  It 
consisted  of  a slightly  curved  cylindrical  case, 
the  interior  of  which  could  be  seen  through 
holes  in  the  sides  and  at  either  end.  The  pine- 
leaves  had  all  been  drawn  in  by  their  bases; 
and  the  sharp  points  of  the  needles  had  been 
pressed  into  the  lining  of  voided  earth.  Had 
this  not  been  effectually  done,  the  sharp  points 
would  have  prevented  the  retreat  of  the  worms 
into  their  burrows;  and  these  structures  would 
have  resembled  traps  armed  with  converging 
points  of  wire,  rendering  the  ingress  of  an  ani- 
mal easy  and  its  egress  difficult  or  impossible. 
The  skill  shown  by  these  worms  is  noteworthy 


Ch.IL  CONSTRUCTION  OF  THEIR  BURROWS.  1 15 

and  is  the  more  remarkable,  as  the  Scotch  pine 
is  not  a native  of  this  district. 

After  having  examined  these  burrows  made 
by  worms  in  confinement,  I looked  at  those  in 
a flower-bed  near  some  Scotch  pines.  These 
had  all  been  plugged  up  in  the  ordinary  man- 
ner with  the  leaves  of  this  tree,  drawn  in  for  a 
length  of  from  1 to  1^  inch;  but  the  mouths  of 
many  of  them  were  likewise  lined  with  them, 
mingled  with  fragments  of  other  kinds  of 
leaves,  drawn  in  to  a depth  of  4 or  5 inches. 
Worms  often  remain,  as  formerly  stated,  for 
a long  time  close  to  the  mouths  of  their  bur- 
rows, apparently  for  warmth;  and  the  basket- 
like structures  formed  of  leaves  would  keep 
their  bodies  from  coming  into  close  contact 
with  the  cold  damp  earth.  That  they  habitu- 
ally rested  on  the  pine-leaves,  was  rendered 
probable  by  their  clean  and  almost  polished 
surfaces. 

The  burrows  which  run  far  down  into  the 
ground,  generally,  or  at  least  often,  terminate 
in  a little  enlargement  or  chamber.  Here,  ac- 
cording to  Hoffmeister,  one  of  several  worms 
pass  the  winter  rolled  up  into  a ball.  Mr.  Lind- 


n6 


HABITS  OF  WORMS. 


Chap.  II. 


say  Carnagie  informed  me  (1838)  that  he  had 
examined  many  burrows  over  a stone-quarry 
in  Scotland,  where  the  overlying  boulder-clav 
and  mould  had  recently  been  cleared  away, 
and  a little  vertical  cliff  thus  left.  In  several 
cases  the  same  burrow  was  a little  enlarged  at 
two  or  three  points  one  beneath  the  other; 
and  all  the  burrows  terminated  in  a rather 
large  chamber,  at  a depth  of  7 or  8 feet  from 
the  surface.  These  chambers  contained  many 
small  sharp  bits  of  stone  and  husks  of  flax- 
seeds. They  must  also  have  contained  living 
seeds,  for  on  the  following  spring  Mr.  Carnagie 
saw  grass-plants  sprouting  out  of  some  of  the 
intersected  chambers.  I found  at  Abinger  in 
Surrey  two  burrows  terminating  in  similar 
chambers  at  a depth  of  36  and  41  inches,  and 
these  were  lined  or  paved  with  little  pebbles, 
about  as  large  as  mustard  seeds;  and  in  one  of 
the  chambers  there  was  a decayed  oat-grain, 
with  its  husk.  Hensen  likewise  states  that 
the  bottoms  of  the  burrows  are  lined  with  little 
stones;  and  where  these  could  not  be  procured, 
seeds,  apparently  of  the  pear,  had  been  used, 
as  many  as  fifteen  having  been  carried  down 


Ch.  II.  CONSTRUCTION  OF  THEIR  BURROWS.  117 

into  a single  burrow,  one  of  which  had  ger- 
minated.* We  thus  see  how  easily  a botanist 
might  be  deceived  who  wished  to  learn  how 
long  deeply  buried  seeds  remained  alive,  if  he 
were  to  collect  earth  from  a considerable  depth, 
on  the  supposition  that  it  could  contain  only 
seeds  which  had  long  lain  buried.  It  is  proba- 
ble that  the  little  stones,  as  well  as  the  seeds, 
are  carried  down  from  the  surface  by  being 
swallowed;  for  a surprising  number  of  glass 
beads,  bits  of  tile  and  of  glass  were  certainly 
thus  carried  down  by  worms  kept  in  pots;  but 
some  may  have  been  carried  down  within  their 
mouths.  The  sole  conjecture  which  I can 
form  why  worms  line  their  winter  quarters 
with  little  stones  and  seeds,  is  to  prevent  their 
closely  coiled-up  bodies  from  coming  into  close 
contact  with  the  surrounding  cold  soil;  and 
such  contact  would  perhaps  interfere  with 
their  respiration  which  is  effected  by  the  skin 
alone. 

A worm  after  swallowing  earth,  whether 
for  making  its  burrow  or  for  food,  soon  comes 

* “ Zeitschrift  fur  wissenschaft.  Zoolog.,”  B.  xxviii.  1877,  p. 


356. 


1 1 8 


HABITS  OF  WORMS. 


Chap.  II. 


to  the  surface  to  empty  its  body.  The  ejected 
earth  is  thoroughly  mingled  with  the  intestinal 
secretions,  and  is  thus  rendered  viscid.  After 
being  dried  it  sets  hard.  I have  watched 
worms  during  the  act  of  ejection,  and  when 
the  earth  was  in  a very  liquid  state  it  was  eject- 
ed in  little  spurts,  and  when  not  so  liquid  by  a 
slow  peristaltic  movement.  It  is  not  cast  in- 
differently on  any  side,  but  with  some  care, 
first  on  one  and  then  on  another  side;  the  tail 
being  used  almost  like  a trowel.  As  soon  as  a 
little  heap  is  formed,  the  worm  apparently 
avoids,  for  the  sake  of  safety,  protruding  its 
tail;  and  the  earthy  matter  is  forced  up 
through  the  previously  deposited  soft  mass. 
The  mouth  of  the  same  burrow  is  used  for  this 
purpose  for  a considerable  time.  In  the  case 
of  the  tower-like  castings  (see  Fig.  2)  near 
Nice,  and  of  the  similar  but  still  taller  towers 
from  Bengal  (hereafter  to  be  described  and 
figured)  a considerable  degree  of  skill  is  exhib- 
ited in  their  construction.  Dr.  King  also  ob- 
served that  the  passage  up  these  towers  hardly 
ever  ran  in  the  same  exact  line  with  the  under- 
lying burrow,  so  that  a thin  cylindrical  object 


Chap.II.  EJECTION  OF  THEIR  CASTINGS.  i jg 

such  as  a haulm  of  grass,  could  not  be  passed 
down  the  tower  into  the  burrow;  and  this 
change  of  direction  probably  serves  in  some 
manner  as  a protection.  When  a worm  comes 
to  the  surface  to  eject  earth,  the  tail  pro- 
trudes, but  when  it  collects  leaves  its  head 
must  protrude.  Worms  therefore  must  have 
the  power  of  turning  round  in  their  closely- 
fitting  burrows;  and  this,  as  it  appears  to  us, 
would  be  a difficult  feat. 

Worms  do  not  always  eject  their  castings 
on  the  surface  of  the  ground.  When  they  can 
find  any  cavity,  as  when  burrowing  in  newly 
turned-up  earth,  or  between  the  stems  of 
banked-up  plants,  they  deposit  their  castings 
in  such  places.  So  again  any  hollow  beneath 
a large  stone  lying  on  the  surface  of  the 
ground,  is  soon  filled  up  with  their  castings. 
According  to  Hensen,  old  burrows  are  habitu- 
ally used  for  this  purpose;  but  as  far  as  my  ex- 
perience serves,  this  is  not  the  case,  excepting 
with  those  near  the  surface  in  recently  dug 
ground.  I think  that  Hensen  may  have  been 
deceived  by  the  walls  of  old  burrows,  lined 
with  black  earth,  having  sunk  in  or  collapsed; 


120 


HABITS  OF  WORMS. 


Chap.  II. 


for  black  streaks  are  thus  left,  and  these  are 
conspicuous  when  passing  through  light-col- 
oured soil,  and  might  be  mistaken  for  corh- 
pletely  filled-up  burrows. 

It  is  certain  that  old  burrows  collapse  in 
the  course  of  time;  for  as  we  shall  see  in  the 
next  chapter,  the  fine  earth  voided  by  worms, 
if  spread  out  uniformly,  would  form  in  many 
places  in  the  course  of  a year  a layer  £ of  an 
inch  in  thickness;  so  that  at  any  rate  this  large 
amount  is  not  deposited  within  the  old  unused 
burrows.  If  the  burrows  did  not  collapse,  the 
whole  ground  would  be  first  thickly  riddled 
with  holes  to  a depth  of  about  ten  inches,  and 
in  fifty  years  a hollow  unsupported  space,  ten 
inches  in  depth,  would  be  left.  The  holes  left 
by  the  decay  of  successively  formed  roots  of 
trees  and  plants  must  likewise  collapse  in  the 
course  of  time. 

The  burrows  of  worms  run  down  perpen- 
dicularly or  a little  obliquely,  and  where  the 
soil  is  at  all  argillaceous,  there  is  no  difficulty 
in  believing  that  the  walls  would  slowly  flow 
or  slide  inwards  during  very  wet  weather. 
When,  however,  the  soil  is  sandy  or  mingled 


Chap.  II.  THE  COLLAPSE  OF  OLD  BURROWS.  I2l 


with  many  small  stones,  it  can  hardly  be  vis- 
cous enough  to  flow  inwards  during  even  the 
wettest  weather;  but  another  agency  may  here 
come  into  play.  After  much  rain  the  ground 
swells,  and  as  it  cannot  expand  laterally,  the 
surface  rises;  during  dry  weather  it  sinks 
again.  For  instance,  a large  flat  stone  laid’ on 
the  surface  of  a field  sank  3.33  mm.  whilst  the 
weather  was  dry  between  May  9th  and  June 
13th,  and  rose  1.91  mm.  between  September 
7th  and  19th,  much  rain  having  fallen  during 
the  latter  part  of  this  time.  During  frosts  and 
thaws  the  movements  were  twice  as  great. 
These  observations  were  made  by  my  son  Hor- 
ace, who  will  hereafter  publish  an  account  of 
the  movements  of  this  stone  during  successive 
wet  and  dry  seasons,  and  of  the  effects  of  its 
being  undermined  by  worms.  Now  when  the 
ground  swells,  if  it  be  penetrated  by  cylindrical 
holes,  such  as  worm-burrows,  their  walls  will 
tend  to  yield  and  be  pressed  inwards;  and  the 
yielding  will  be  greater  in  the  deeper  parts 
(supposing  the  whole  to  be  equally  moistened) 
from  the  greater  weight  of  the  superincum- 
bent soil  which  has  to  be  raised,  than  in  the 
9 


122 


HABITS  OF  WORMS. 


Chap.  II. 


parts  near  the  surface.  When  the  ground 
dries,  the  walls  will  shrink  a little  and  the  bur- 
rows will  be  a little  enlarged.  Their  enlarge- 
ment, however,  through  the  lateral  contrac- 
tion of  the  ground,  will  not  be  favoured,  but 
rather  opposed,  by  the  weight  of  the  superin- 
cumbent soil. 

Distribution  of  Worms. — Earth-worms  are 
found  in  all  parts  of  the  world,  and  some  of 
the  genera  have  an  enormous  range.*  They 
inhabit  the  most  isolated  islands;  they  abound 
in  Iceland,  and  are  known  to  exist  in  the  West 
Indies,  St.  Helena,  Madagascar,  New  Cale- 
donia and  Tahiti.  In  the  Antarctic  regions, 
worms  from  Kerguelen  Land  have  been  de- 
scribed by  Ray  Lankester;  and  I found  them 
in  the  Falkland  Islands.  How  they  reach  such 
isolated  islands  is  at  present  quite  unknown. 
They  are  easily  killed  by  salt-water,  and  it  does 
not  appear  probable  that  young  worms  or  their 
egg-capsules  could  be  carried  in  earth  adhering 
to  the  feet  or  beaks  of  land-birds.  Moreover 
Kerguelen  Land  is  not  now  inhabited  by  any 
land-bird. 

* Perrier,  “ Archives  de  Zoolog.  exper.,”  tom.  3,  p.  378,  1874. 


Chap.  II.  THEIR  WIDE  DISTRIBUTION.  123 

In  this  volume  we  are  chiefly  concerned 
with  the  earth  cast  up  by  worms,  and  I have 
gleaned  a few  facts  on  this  subject  with  re- 
spect to  distant  lands.  Worms  throw  up 
plenty  of  castings  in  the  United  States.  In 
Venezuela,  castings,  probably  ejected  by  spe- 
cies of  Urochseta,  are  common  in  the  gardens 
and  fields,  but  not  in  the  forests,  as  I hear  from 
Dr.  Ernst  of  Caracas.  He  collected  156  cast- 
ings from  the  court-yard  of  his  house,  having 
an  area  of  200  square  yards.  They  varied  in 
bulk  from  half  a cubic  centimetre  to  five  cubic 
centimetres,  and  were  on  an  average  three  cu- 
bic centimetres.  They  were,  therefore,  of 
small  size  in  comparison  with  those  often 
found  in  England;  for  six  large  castings  from 
a field  near  my  house  averaged  16  cubic  centi- 
metres. Several  species  of  earth-worms  are 
common  in  St.  Catharina  in  South  Brazil,  and 
Fritz  Muller  informs  me  “ that  in  most  parts 
of  the  forests  and  pasture-lands,  the  whole  soil, 
to  a depth  of  a quarter  of  a metre,  looks  as  if  it 
had  passed  repeatedly  through  the  intestines 
of  earth-worms,  even  where  hardly  any  cast- 
ings are  to  be  seen  on  the  surface.”  A gigan- 


124  HABITS  OF  WORMS.  Chap.  II. 

tic  but  very  rare  species  is  found  there,  the 
burrows  of  which  are  sometimes  even  two  cen- 
timetres or  nearly  f of  an  inch  in  diameter, 
and  which  apparently  penetrate  the  ground  to 
a great  depth. 

In  the  dry  climate  of  New  South  Wales,  I 
hardly  expected  that  worms  would  be  com- 
mon; but  Dr.  G.  Krefft  of  Sydney,  to  whom 
I applied,  after  making  inquiries  from  gar- 
deners and  others,  and  from  his  own  observa- 
tions, informs  me  that  their  castings  abound. 
He  sent  me  some  collected  after  heavy  rain, 
and  they  consisted  of  little  pellets,  about  .15 
inch  in  diameter;  and  the  blackened  sandy 
earth  of  which  they  were  formed  still  cohered 
with  considerable  tenacity. 

The  late  Mr.  John  Scott  of  the  Botanic 
Gardens  near  Calcutta  made  many  observa- 
tions for  me  on  worms  living  under  the  hot 
and  humid  climate  of  Bengal.  The  castings 
abound  almost  everywhere,  in  jungles  and  in 
the  open  ground,  to  a greater  degree,  as  he 
thinks,  than  in  England.  After  the  water  has 
subsided  from  the  flooded  rice-fields,  the  whole 
surface  very  soon  becomes  studded  with  cast- 


Chap.  II.  THEIR  WIDE  DISTRIBUTION. 


125 


ings — a fact  which  much  surprised  Mr.  Scott, 
as  he  did  not  know  how  long  worms  could 
survive  beneath  water.  They  cause  much 
trouble  in  the  Botanic  garden,  “ for  some  of 
the  finest  of  our  lawns  can  be  kept  in  any- 
thing like  order  only  by  being  almost  daily 
rolled;  if  left  undisturbed  for  a few  days  they 
become  studded  with  large  castings.”  These 
closely  resemble  those  described  as  abounding 
near  Nice;  and  they  are  probably  the  work  of 
a species  of  Perichseta.  They  stand  up  like 
towers,  with  an  open  passage  in  the  centre. 

A figure  of  one  of  these  castings  from  a 
photograph  is  here  given  (Fig.  3).  The  largest 
received  by  me  was  3^  inches  in  height  and 
1.35  inch  in  diameter;  another  was  only  f inch 
in  diameter  and  2f  in  height.  In  the  following 
year,  Mr.  Scott  measured  several  of  the  lar- 
gest; one  was  6 inches  in  height  and  nearly  1^ 
in  diameter:  two  others  were  5 inches  in  height 
and  respectively  2 and  rather  more  than  2\ 
inches  in  diameter.  The  average  weight  of  the 
22  castings  sent  to  me  was  35  grammes  (i  j 
oz.);  and  one  of  them  weighed  44.8  grammes 
(or  2 oz.).  All  these  castings  were  thrown 


126 


HABITS  OF  WORMS. 


Chap.  II. 


up  either  in  one  night  or  in  two.  Where  the 
ground  in  Bengal  is  dry,  as  under  large  trees, 


Fig.  3. — A tower-like  casting,  probably  ejected  by  a species  of 
Perichseta,  from  the  Botanic  Garden,  Calcutta  ; of  natural 
size,  engraved  from  a photograph. 


castings  of  a different  kind  are  found  in  vast 


Chap.  II.  THEIR  WIDE  DISTRIBUTION. 


127 


numbers;  these  consist  of  little  oval  or  conical 
bodies,  from  about  the  gV  to  rather  above  TV 
of  an  inch  in  length.  They  are  obviously  void- 
ed by  a distinct  species  of  worms. 

The  period  during  which  worms  near  Cal- 
cutta display  such  extraordinary  activity  lasts 
for  only  a little  over  two  months,  namely,  dur- 
ing the  cool  season  after  the  rains.  At  this 
time  they  are  generally  found  within  about  10 
inches  beneath  the  surface.  During  the  hot 
season  they  burrow  to  a greater  depth,  and  are 
then  found  coiled  up  and  apparently  hybernat- 
ing.  Mr.  Scott  has  never  seen  them  at  a 
greater  depth  than  2\  feet,  but  has  heard  of 
their  having  been  found  at  4 feet.  Within  the 
forests,  fresh  castings  may  be  found  even  dur- 
ing the  hot  season.  The  worms  in  the  Bo- 
tanic garden,  during  the  cool  and  dry  season, 
draw  many  leaves  and  little  sticks  into  the 
mouths  of  their  burrows,  like  our  English 
worms;  but  they  rarely  act  in  this  manner  dur- 
ing the  rainy  season. 

Mr.  Scott  saw  worm-castings  on  the  lofty 
mountains  of  Sikkim  in  North  India.  In 
South  India  Dr.  King  found  in  one  place,  on 


128 


HABITS  OF  WORMS. 


Chap.  II. 


the  plateau  of  the  Nilgiris,  at  an  elevation  of 
7000  feet,  “ a good  many  castings,”  which  are 
interesting  for  their  great  size.  The  worms 
which  eject  them  are  seen  only  during  the  wet 
season,  and  are  reported  to  be  from  12  to  15 


Fig.  4. — A casting  from  the  Nilgiri  Mountains  in  South  India; 
of  natural  size,  engraved  from  a photograph. 


inches  in  length,  and  as  thick  as  a man’s  little 
finger.  These  castings  were  collected  by  Dr. 
King  after  a period  of  no  days  without  any 
rain;  and  they  must  have  been  ejected  either 
during  the  north-east  or  more  probably  during 


Chap.IL  THEIR  WIDE  DISTRIBUTION.  129 

the  previous  south-west  monsoon;  for  their 
surfaces  had  suffered  some  disintegration  and 
they  were  penetrated  by  many  fine  roots.  A 
drawing  is  here  given  (Fig.  4)  of  one  which 
seems  to  have  best  retained  its  original  size 
and  appearance.  Notwithstanding  some  loss 
from  disintegration,  five  of  the  largest  of  these 
castings  (after  having  been  well  sun-dried) 
weighed  each  on  an  average  89.5  grammes,  or 
above  3 oz.;  and  the  largest  weighed  123.14 
grammes,  or  4^-  oz., — that  is  above  a quarter 
of  a pound!  The  largest  convolutions  were 
rather  more  than  one  inch  in  diameter;  but  it 
is  probable  that  they  had  subsided  a little 
whilst  soft,  and  that  their  diameters  had  thus 
been  increased.  Some  had  flowed  so  much 
that  they  now  consisted  of  a pile  of  almost  flat 
confluent  cakes.  All  were  formed  of  fine, 
rather  light-coloured  earth,  and  were  surpris- 
ingly hard  and  compact,  owing  no  doubt  to 
the  animal  matter  by  which  the  particles  of 
earth  had  been  cemented  together.  They  did 
not  disintegrate,  even  when  left  for  some 
hours  in  water.  Although  they  had  been  cast 
up  on  the  surface  of  gravelly  soil,  they  con- 


130 


HABITS  OF  WORMS. 


Chap.  II. 


tained  extremely  few  bits  of  rock,  the  largest 
of  which  was  only  .15  inch  in  diameter. 

Dr.  King  saw  in  Ceylon  a worm  about  2 
feet  in  length  and  \ inch  in  diameter;  and  he 
was  told  that  it  was  a very  common  species 
during  the  wet  season.  These  worms  must 
throw  up  castings  at  least  as  large  as  those  on 
the  Nilgiri  Mountains;  but  Dr.  King  saw 
none  during  his  short  visit  to  Ceylon.  Suffi- 
cient facts  have  now  been  given,  showing  that 
worms  do  much  work  in  bringing  up  fine  earth 
to  the  surface  in  most  or  all  parts  of  the  world, 
and  under  the  most  different  climates. 


CHAPTER  III. 


THE  AMOUNT  OF  FINE  EARTH  BROUGHT  UP 
BY  WORMS  TO  THE  SURFACE. 

Rate  at  which  various  objects  strewed  on  the  surface  of  grass- 
fields  are  covered  up  by  the  castings  of  worms — The  burial  of 
a paved  path — The  slow  subsidence  of  great  stones  left  on  the 
surface — The  number  of  worms  which  live  within  a given 
space — The  weight  of  earth  ejected  from  a burrow,  and  from 
all  the  burrows  within  a given  space — The  thickness  of  the 
layer  of  mould  which  the  castings  on  a given  space  would 
form  within  a given  time  if  uniformly  spread  out — The  slow 
rate  at  which  mould  can  increase  to  a great  thickness — 
Conclusion. 

We  now  come  to  the  more  immediate  sub- 
ject of  this  volume,  namely,  the  amount  of 
earth  which  is  brought  up  by  worms  from  be- 
neath the  surface,  and  is  afterwards  spread 
out  more  or  less  completely  by  the  rain  and 
wind.  The  amount  can  be  judged  of  by  two 
methods, — by  the  rate  at  which  objects  left 

on  the  surface  are  buried,  and  more  accurately 

131 


132  AMOUNT  OF  EARTH  Chap.  III. 

by  weighing  the  quantity  brought  up  within  a 
given  time.  We  will  begin  with  the  first 
method,  as  it  was  first  followed. 

Near  Maer  Hall  in  Staffordshire,  quick- 
lime had  been  spread  about  the  year  1827 
thickly  over  a field  of  good  pasture-land,  which 
had  not  since  been  ploughed.  Some  square 
holes  were  dug  in  this  field  in  the  beginning  of 
October,  1837;  and  the  sections  showed  a layer 
of  turf  formed  by  the  matted  roots  of  the 
grasses,  ^ inch  in  thickness,  beneath  which,  at 
a depth  of  2\  inches  (or  3 inches  from  the  sur- 
face), a layer  of  the  lime  in  powder  or  in  small 
lumps  could  be  distinctly  seen  running  all 
round  the  vertical  sides  of  the  holes.  The 
soil  beneath  the  layer  of  lime  was  either  gravel- 
ly or  of  a coarse  sandy  nature,  and  differed  con- 
siderably in  appearance  from  the  overlying 
dark-coloured  fine  mould.  Coal-cinders  had 
been  spread  over  a part  of  this  same  field  either 
in  the  year  1833  or  1834;  and  when  the  above 
holes  were  dug,  that  is  after  an  interval  of  3 
or  4 years,  the  cinders  formed  a line  of  black 
spots  round  the  holes,  at  a depth  of  1 inch  be- 
neath the  surface,  parallel  to  and  above  the 


Chap.  III.  BROUGHT  UP  BY  WORMS.  133 

white  layer  of  lime.  Over  another  part  of  this 
field  cinders  had  been  strewed,  only  about  half- 
a-year  before,  and  these  either  still  lay  on  the 
surface  or  were  entangled  among  the  roots 
of  the  grasses;  and  I here  saw  the  commence- 
ment of  the  burying  process,  for  worm-cast- 
ings had  been  heaped  on  several  of  the  smaller 
fragments.  After  an  interval  of  4§  years  this 
field  was  re-examined,  and  now  the  two  layers 
of  lime  and  cinders  were  found  .almost  every- 
where at  a greater  depth  than  before  by  nearly 
1 inch,  we  will  say  by  § of  an  inch.  Therefore 
mould  to  an  average  thickness  of  .22  of  an 
inch  had  been  annually  brought  up  by  the 
worms,  and  had  been  spread  over  the  surface 
of  this  field. 

Coal-cinders  had  been  strewed  over  an- 
other field,  at  a date  which  could  not  be  posi- 
tively ascertained,  so  thickly  that  they  formed 
(October,  1837)  a layer,  1 inch  in  thickness  at 
a depth  of  about  3 inches  from  the  surface. 
The  layer  was  so  continuous  that  the  overly- 
ing dark  vegetable  mould  was  connected  with 
the  sub-soil  of  red  clay  only  by  the  roots  of  the 
grasses;  and  when  these  were  broken,  the 


134 


AMOUNT  OF  EARTH 


Chap.  III. 


mould  and  the  red  clay  fell  apart.  In  a third 
field,  on  which  coal-cinders  and  burnt  marl 
had  been  strewed  several  times  at  unknown 
dates,  holes  were  dug  in  1842;  and  a layer  of 
cinders  could  be  traced  at  a depth  of  3^  inches, 
beneath  which  at  a depth  of  9^  inches  from 
the  surface  there  was  a line  of  cinders  together 
with  burnt  marl.  On  the  sides  of  one  hole 
there  were  two  layers  of  cinders,  at  2 and  3! 
inches  beneath  the  surface;  and  below  them  at 
a depth  in  parts  of  9^,  and  in  other  parts  of 
10J  inches  there  were  fragments  of  burnt  marl. 
In  a fourth  field  two  layers  of  lime,  one  above 
the  other,  could  be  distinctly  traced,  and  be- 
neath them  a layer  of  cinders  and  burnt  marl 
at  a depth  of  from  10  to  12  inches  below  the 
surface. 

A piece  of  waste,  swampy  land  was  en- 
closed, drained,  ploughed,  harrowed  and  thick- 
ly covered  in  the  year  1822  with  burnt  marl 
and  cinders.  It  was  sowed  with  grass  seeds, 
and  now  supports  a tolerably  good  but  coarse 
pasture.  Holes  were  dug  in  this  field  in  1837, 
or  15  years  after  its  reclamation,  and  we  see  in 
the  accompanying  diagram  (Fig.  5),  reduced 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


135 


to  half  of  the  natural  scale,  that  the  turf  was 
inch  thick,  beneath  which  there  was  a layer  of 


Fig.  5. — Section,  reduced  to  half  the  natural  scale,  of  the  vege- 
table mould  in  a field,  drained  and  reclaimed  fifteen  years 
previously  ; A,  turf  ; B,  vegetable  mould  without  any  stones  ; 
C,  mould  with  fragments  of  burnt  marl,  coal-cinders  and 
quartz  pebbles  ; D,  sub-soil  of  black,  peaty  sand  with  quartz 
pebbles. 


vegetable  mould  2^  inches  thick.  This  layer 
did  not  contain  fragments  of  any  kind;  but  be- 


136  AMOUNT  OF  EARTH  Chap.  III. 

neath  it  there  was  a layer  of  mould,  1^  inch 
in  thickness,  full  of  fragments  of  burnt  marl, 
conspicuous  from  their  red  colour,  one  of 
which  near  the  bottom  was  an  inch  in  length; 
and  other  fragments  of  coal-cinders  together 
with  a few  white  quartz  pebbles.  Beneath  this 
layer  and  at  a depth  of  \\  inches  from  the  sur- 
face, the  original  black,  peaty,  sandy  soil  with 
a few  quartz  pebbles  was  encountered.  Here 
therefore  the  fragments  of  burnt  marl  and  cin- 
ders had  been  covered  in  the  course  of  15  years 
by  a layer  of  fine  vegetable  mould,  only  2\ 
inches  in  thickness,  excluding  the  turf.  Six 
and  a half  years  subsequently  this  field  was  re- 
examined, and  the  fragments  were  now  found 
at  from  4 to  5 inches  beneath  the  surface.  So 
that  in  this  interval  of  6J  years,  about  1^  inch 
of  mould  had  been  added  to  the  superficial 
layer.  I am  surprised  that  a greater  quantity 
had  not  been  brought  up  during  the  whole  2i-§ 
years,  for  in  the  closely  underlying  black,  peaty 
soil  there  were  many  worms.  It  is,  however, 
probable  that  formerly,  whilst  the  land  re- 
mained poor,  worms  were  scanty;  and  the 
mould  would  then  have  accumulated  slowly. 


Chap.  III.  BROUGHT  UP  BY  WORMS.  137 

The  average  annual  increase  of  thickness  for 
the  whole  period  is  .19  of  an  inch. 

Two  other  cases  are  worth  recording.  In 
the  spring  of  1835,  a field,  which  had  long  ex- 
isted as  poor  pasture  and  was  so  swampy  that 
it  trembled  slightly  when  stamped  on,  was 
thickly  covered  with  red  sand  so  that  the 
whole  surface  appeared  at  first  bright  red. 
When  holes  were  dug  in  this  field  after  an  in- 
terval of  about  years,  the  sand  formed  a 
layer  at  a depth  of  f in.  beneath  the  surface. 
In  1842  (i.  e.,  7 years  after  the  sand  had  been 
laid  on)  fresh  holes  were  dug,  and  now  the  red 
sand  formed  a distinct  layer,  2 inches  beneath 
the  surface,  or  1^  inch  beneath  the  turf;  so 
that  on  an  average,  .21  inches  of  mould  had 
been  annually  brought  to  the  surface.  Im- 
mediately beneath  the  layer  of  red  sand,  the 
original  substratum  of  black  sandy  peat  ex- 
tended. 

A grass  field,  likewise  not  far  from  Maer 
Hall,  had  formerly  been  thickly  covered  with 
marl,  and  was  then  left  for  several  years  as 
pasture;  it  was  afterwards  ploughed.  A 

friend  had  three  trenches  dug  in  this  field  28 

10 


138 


AMOUNT  OF  EARTH 


Chap.  III. 


years  after  the  application  of  the  marl,*  and  a 
layer  of  the  marl  fragments  could  be  traced  at 
a depth,  carefully  measured,  of  12  inches  in 
some  parts,  and  of  14  inches  in  other  parts. 
This  difference  in  depth  depended  on  the  layer 
being  horizontal,  whilst  the  surface  consisted 
of  ridges  and  furrows  from  the  field  having 
been  ploughed.  The  tenant  assured  me  that  it 
had  never  been  turned  up  to  a greater  depth 
than  from  6 to  8 inches;  and  as  the  fragments 
formed  an  unbroken  horizontal  layer  from  12 
to  14  inches  beneath  the  surface,  these  must 
have  been  buried  by  the  worms  whilst  the  land 
was  in  pasture  before  it  was  ploughed,  for 
otherwise  they  would  have  been  indiscrimi- 
nately scattered  by  the  plough  throughout  the 
whole  thickness  of  the  soil.  Four-and-a-half 
years  afterwards  I had  three  holes  dug  in  this 
field,  in  which  potatoes  had  been  lately 

* This  case  is  given  in  a postscript  to  my  paper  in  the 
“ Transact.  Geolog.  Soc.”  (vol.  v.  p.  505),  and  contains  a serious 
error,  as  in  the  account  received  I mistook  the  figure  30  for  80. 
The  tenant,  moreover,  formerly  said  that  he  had  marled  the  field 
thirty  years  before,  but  was  now  positive  that  this  was  done  in 
1809,  that  is  twenty-eight  years  before  the  first  examination  of 
the  field  by  my  friend.  The  error,  as  far  as  the  figure  80  is 
concerned,  was  corrected  in  an  article  by  me,  in  the  “ Gardeners’ 
Chronicle,”  1844,  p.  218. 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


139 


planted,  and  the  layer  of  marl-fragments  was 
now  found  13  inches  beneath  the  bottoms  of 
the  furrows,  and  therefore  probably  15  inches 
beneath  the  general  level  of  the  field.  It 
should,  however,  be  observed  that  the  thick- 
ness of  the  blackish  sandy  soil,  which  had 
been  thrown  up  by  the  worms  above  the  marl- 
fragments  in  the  course  of  32^  years,  would 
have  measured  less  than  1 5 inches,  if  the  field 
had  always  remained  as  pasture,  for  the  soil 
would  in  this  case  have  been  much  more  com- 
pact. The  fragments  of  marl  almost  rested 
on  an  undisturbed  sub-stratum  of  white  sand 
with  quartz  pebbles;  and  as  this  would  be 
little  attractive  to  worms,  the  mould  would 
hereafter  be  very  slowly  increased  by  their 
action. 

We  will  now  give  some  cases  of  the  action 
of  worms,  on  land  differing  widely  from  the 
dry  sandy  or  the  swampy  pastures  just  de- 
scribed. The  chalk  formation  extends  all 
round  my  house  in  Kent;  and  its  surface,  from 
having  been  exposed  during  an  immense 
period  to  the  dissolving  action  of  rain-water, 
is  extremely  irregular,  being  abruptly  fes- 


140 


AMOUNT  OF  EARTH 


Chap.  III. 


tooned  and  penetrated  by  many  deep  well-like 
cavities.*  During  the  dissolution  of  the  chalk, 

* These  pits  or  pipes  are  still  in  process  of  formation.  During 
the  last  forty  years  I have  seen  or  heard  of  five  cases,  in  which  a 
circular  space,  several  feet  in  diameter,  suddenly  fell  in,  leaving 
on  the  field  an  open  hole  with  perpendicular  sides,  some  feet  in 
depth.  This  occurred  in  one  of  my  own  fields,  whilst  it  was 
being  rolled,  and  the  hinder  quarters  of  the  shaft  horse  fell  in  ; two 
or  three  cart-loads  of  rubbish  were  required  to  fill  up  the  hole. 
The  subsidence  occurred  where  there  was  a broad  depression,  as 
if  the  surface  had  fallen  in  at  several  former  periods.  I heard 
of  a hole  which  must  have  been  suddenly  formed  at  the  bottom 
of  a small  shallow  pool,  where  sheep  had  been  washed  during 
many  years,  and  into  which  a man  thus  occupied  fell  to  his  great 
terror.  The  rain-water  over  this  whole  district  sinks  perpen- 
dicularly into  the  ground,  but  the  chalk  is  more  porous  in  certain 
places  than  in  others.  Thus  the  drainage  from  the  overlying 
clay  is  directed  to  certain  points,  where  a greater  amount  of  cal- 
careous matter  is  dissolved  than  elsewhere.  Even  narrow  open 
channels  are  sometimes  formed  in  the  solid  chalk.  As  the  chalk 
is  slowly  dissolved  over  the  whole  country,  but  more  in  some 
parts  than  in  others,  the  undissolved  residue — that  is,  the  over- 
lying  mass  of  red  clay  with  flints — likewise  sinks  slowly  down, 
and  tends  to  fill  up  the  pipes  or  cavities.  But  the  upper  part 
of  the  red  clay  holds  together,  aided  probably  by  the  roots  of 
plants,  for  a longer  time  than  the  lower  parts,  and  thus  forms 
a roof,  which  sooner  or  later  falls  in,  as  in  the  above-mentioned 
five  cases.  The  downward  movement  of  the  clay  may  be  com- 
pared with  that  of  a glacier,  but  is  incomparably  slower  ; and  this 
movement  accounts  for  a singular  fact,  namely  that  the  much- 
elongated  flints  which  are  embedded  in  the  chalk  in  a nearly 
horizontal  position,  are  commonly  found  standing  nearly  or  quite 
upright  in  the  red  clay.  This  fact  is  so  common  that  the  work- 
men assured  me  that  this  was  their  natural  position.  I roughly 
measured  one  which  stood  vertically,  and  it  was  of  the  same 
length  and  of  the  same  relative  thickness  as  one  of  my  arms. 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


141 

the  insoluble  matter,  including  a vast  number 
of  unrolled  flints  of  all  sizes,  has  been  left  on 
the  surface  and  forms  a bed  of  stiff  red  clay, 
full  of  flints,  and  generally  from  6 to  14  feet  in 
thickness.  Over  the  red  clay,  wherever  the 
land  has  long  remained  as  pasture,  there  is  a 
layer  a few  inches  in  thickness,  of  dark-col- 
oured vegetable  mould. 

A quantity  of  broken  chalk  was  spread, 
on  December  20,  1842,  over  a part  of  a field 
near  my  house,  which  had  existed  as  pasture 
certainly  for  30,  probably  for  twice  or  thrice 
as  many  years.  The  chalk  was  laid  on  the  land 
for  the  sake  of  observing  at  some  future  period 
to  what  depth  it  would  become  buried.  At 
the  end  of  Novemter,  1871,  that  is  after  an  in- 
terval of  29  years,  a trench  was  dug  across  this 
part  of  the  field;  and  a line  of  white  nodules 

These  elongated  flints  must  get  placed  in  their  upright  position, 
on  the  same  principle  that  a trunk  of  a tree  left  on  a glacier 
assumes  a position  parallel  to  the  line  of  motion.  The  flints 
in  the  clay  which  form  almost  half  its  bulk  are  very  often 
broken,  though  not  rolled  or  abraded  ; and  this  may  be  ac- 
counted for  by  their  mutual  pressure,  whilst  the  whole  mass  is 
subsiding.  I may  add  that  the  chalk  here  appears  to  have  been 
originally  covered  in  parts  by  a thin  bed  of  fine  sand  with  some 
perfectly  rounded  flint  pebbles,  probably  of  Tertiary  age  ; for  such 
sand  often  partly  fills  up  the  deeper  pits  or  cavities  in  the  chalk. 


142 


AMOUNT  OF  EARTH 


Chap.  III. 


could  be  traced  on  both  sides  of  the  trench, 
at  a depth  of  7 inches  from  the  surface.  The 
mould,  therefore  (excluding  the  turf,  had  here 
been  thrown  up  at  an  average  rate  of  .22  inches 
per  year.  Beneath  the  line  of  'chalk  nodules 
there  was  in  parts  hardly  any  fine  earth  free  of 
flints,  while  in  other  parts  there  was  a layer, 
2\  inches  in  thickness.  In  this  latter  case  the 
mould  was  altogether  9J  inches  thick;  and  in 
one  such  spot  a nodule  of  chalk  and  a smooth 
flint  pebble,  both  of  which  must  have  been  left 
at  some  former  time  on  the  surface,  were  found 
at  this  depth.  At  from  1 1 to  12  inches  beneath 
the  surface,  the  undisturbed  reddish  clay,  full 
of  flints,  extended.  The  appearance  of  the 
above  nodules  of  chalk  surprised  me  much  at 
first,  as  they  closely  resembled  water-worn 
pebbles,  whereas  the  freshly-broken  fragments 
had  been  angular.  But  on  examining  the 
nodules  with  a lens,  they  no  longer  appeared 
water-worn,  for  their  surfaces  were  pitted 
through  unequal  corrosion,  and  minute,  sharp 
points,  formed  of  broken  fossil  shells,  projected 
from  them.  It  was  evident  that  the  corners 
of  the  original  fragments  of  chalk  had  been 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


143 


wholly  dissolved,  from  presenting  a large  sur- 
face to  the  carbonic  acid  dissolved  in  the  rain- 
water and  to  that  generated  in  soil  containing 
vegetable  matter,  as  well  as  to  the  humus- 
acids.*  The  projecting  corners  would  also, 
relatively  to  the  other  parts,  have  been  em- 
braced by  a larger  number  of  living  rootlets 
and  these  have  the  power  of  even  attacking 
marble,  as  Sachs  has  shown.  Thus,  in  the 
course  of  29  years,  buried  angular  fragments 
of  chalk  had  been  converted  into  well-rounded 
nodules. 

Another  part  of  this  same  field  was.  mossy, 
and  as  it  was  thought  that  sifted  coal-cinders 
would  improve  the  pasture,  a thick  layer  was 
spread  over  this  part  either  in  1842  or  1843 
and  another  layer  some  years  afterwards.  In 
1871  a trench  was  here  dug,  and  many  cinders 
lay  in  a line  a,t  a depth  of  7 inches  beneath  the 
surface,  with  another  line  at  a depth  of  5^ 
inches  parallel  to  the  one  beneath.  In  another 
part  of  this  field,  which  had  formerly  existed  as 
a separate  one,  and  which  it  was  believed  had 
been  pasture-land  for  more  than  a century, 

* S.  W.  Johnson,  “ How  Crops  Feed,”  1870,  p.  139. 


144 


AMOUNT  OF  EARTH 


Chap.  III. 


trenches  were  dug  to  see  how  thick  the  veg- 
etable mould  was.  By  chance  the  first  trench 
was  made  at  a spot  where  at  some  former 
period,  certainly  more  than  forty  years  before, 
a large  hole  had  been  filled  up  with  coarse  red 
clay,  flints,  fragments  of  chalk,  and  gravel; 
and  here  the  fine  vegetable  mould  was  only 
from  4^  to  4f  inches  in  thickness.  In  an- 
other and  undisturbed  place,  the  mould  varied 
much  in  thickness,  namely  from  6^  to  8^ 
inches;  beneath  which  a few  small  fragments 
of  brick  were  found  in  one  place.  From  these 
several  cases,  it  would  appear  that  during  the 
last  29  years  mould  has  been  heaped  on  the 
surface  at  an  average  annual  rate  of  from  .2 
to  .22  of  an  inch.  But  in  this  district  when  a 
ploughed  field  is  first  laid  down  in  grass,  the 
mould  accumulates  at  a much  slower  rate. 
The  rate,  also,  must  become  very  much  slower 
after  a bed  of  mould,  several  inches  in  thick- 
ness, has  been  formed;  for  the  worms  then 
live  chiefly  near  the  surface,  and  burrow  down 
to  a greater  depth  so  as  to  bring  up  fresh  earth 
from  below,  only  during  the  winter  when  the 
weather  is  very  cold  (at  which  time  worms 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


145 


were  found  in  this  field  at  a depth  of  26  inches) 
and  during  summer,  when  the  weather  is  very 
dry. 

A field,  which  adjoins  the  one  just  de- 
scribed, slopes  in  one  part  rather  steeply  (viz., 
at  from  io°  to  150);  this  part  was  last 
ploughed  in  1841,  was  then  harrowed  and  left 
to  become  pasture-land.  For  several  years  it 
was  clothed  with  an  extremely  scant  vegeta- 
tion, and  was  so  thickly  covered  with  small  and 
large  flints  (some  of  them  half  as  large  as  a 
child’s  head)  that  the  field  was  always  called  by 
my  sons  “ the  stony  field. ” When  they  ran 
down  the  slope  the  stones  clattered  together. 
I remember  doubting  whether  I should  live  to 
see  these  larger  flints  covered  with  vegetable 
mould  and  turf.  But  the  smaller  stones  dis- 
appeared before  many  years  had  elapsed,  as  did 
every  one  of  the  larger  ones  after  a time;  so 
that  after  thirty  years  (1871)  a horse  could  gal- 
lop over  the  compact  turf  from  one  end  of  the 
field  to  the  other,  and  not  strike  a single  stone 
with  his  shoes.  To  anyone  who  remembered 
the  appearance  of  the  field  in  1842,  the  trans- 
formation was  wonderful.  This  was  certainly 


X46  AMOUNT  OF  EARTH  Chap.  III. 

the  work  of  the  worms,  for  though  castings 
were  not  frequent  for  several  years,  yet  some 
were  thrown  up  month  after  month,  and  these 
gradually  increased  in  numbers  as  the  pasture 
improved.  In  the  year  1871  a trench  was  dug 
on  the  above  slope,  and  the  blades  of  grass 
were  cut  off  close  to  the  roots,  so  that  the 
thickness  of  the  turf  and  of  the  vegetable 
mould  could  be  measured  accurately.  The 
turf  was  rather  less  than  half  an  inch,  and  the 
mould,  which  did  not  contain  any  stones,  2\ 
inches  in  thickness.  Beneath  this  lay  coarse 
clayey  earth  full  of  flints,  like  that  in  any  of 
the  neighbouring  ploughed  fields.  This  coarse 
earth  easily  fell  apart  from  the  overlying  mould 
when  a spit  was  lifted  up.  The  average  rate  of 
accumulation  of  the  mould  during  the  whole 
thirty  years  was  only  .083  inch  per  year  (i.  e., 
nearly  one  inch  in  twelve  years);  but  the  rate 
must  have  been  much  slower  at  first,  and  after- 
wards considerably  quicker. 

The  transformation  in  the  appearance  of  this 
field,  which  had  been  effected  beneath  my  eyes, 
was  afterwards  rendered  the  more  striking, 
when  I examined  in  Knole  Park  a dense  forest 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


147 

of  lofty  beech-trees,  beneath  which  nothing 
grew.  Here  the  ground  was  thickly  strewed 
with  large  naked  stones,  and  worm-castings 
were  almost  wholly  absent.  Obscure  lines  and 
irregularities  on  the  surface  indicated  that  the 
land  had  been  cultivated  some  centuries  ago. 
It  is  probable  that  a thick  wood  of  young 
beech-trees  sprung  up  so  quickly,  that  time 
enough  was  not  allowed  for  worms  to  cover 
up  the  stones  with  their  castings,  before  the 
site  became  unfitted  for  their  existence.  Any- 
how the  contrast  between  the  state  of  the  now 
miscalled  “ stony  field, ” well  stocked  with 
worms,  and  the  present  state  of  the  ground 
beneath  the  old  beech-trees  in  Knole  Park, 
where  worms  appeared  to  be  absent,  was  strik- 
ing. 

A narrow  path  running  across  part  of  my 
lawn  was  paved  in  1843  with  small  flag-stones, 
set  edgeways;  but  worms  threw  up  many  cast- 
ings and  weeds  grew  thickly  between  them. 
During  several  years  the  path  was  weeded  and 
swept;  but  ultimately  the  weeds  and  worms 
prevailed,  and  the  gardener  ceased  to  sweep, 
merely  mowing  off  the  weeds,  as  often  as  the 


148  AMOUNT  OF  EARTH  Chap.  III. 

lawn  was  mowed.  The  path  soon  became  al- 
most covered  up,  and  after  several  years  no 
trace  of  it  was  left.  On  removing,  in  1877,  the 
thin  overlying  layer  of  turf,  the  small  flag- 
stones, all  in  their  proper  places,  were  found 
covered  by  an  inch  of  fine  mould. 

Two  recently  published  accounts  of  sub- 
stances strewed  on  the  surface  of  pasture-land, 
having  become  buried  through  the  action  of 
worms,  may  be  here  noticed.  The  Rev.  H.  C. 
Key  had  a ditch  cut  in  a field,  over  which  coal- 
ashes  had  been  spread,  as  it  was  believed,  eigh- 
teen years  before;  and  on  the  clean-cut  per- 
pendicular sides  of  the  ditch,  at  a depth  of  at 
least  seven  inches,  there  could  be  seen,  for  a 
length  of  60  yards,  “ a distinct,  very  even,  nar- 
row line  of  coal-ashes,  mixed  with  small 
coal,  perfectly  parallel  with  the  top-sward.”  * 
This  parallelism  and  the  length  of  the  section 
gives  interest  to  the  case.  Secondly,  Mr. 
Dancer  states  f that  crushed  bones  had  been 
thickly  strewed  over  a field;  and  “ some  years 
afterwards  ” these  were  found  “ several 

* “ Nature,”  November,  1877,  p.  28. 

f “ Proc.  Phil.  Soc.”  of  Manchester,  1877,  p.  247. 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


149 

inches  below  the  surface,  at  a uniform 
depth.”  Worms  appear  to  act  in  the  same 
manner  in  New  Zealand  as  in  Europe;  for  Pro- 
fessor J.  von  Haast  has  described  * a section 
near  the  coast,  consisting  of  mica-schist,  “ cov- 
ered by  5 or  6 feet  of  loess,  “ above  which 
about  1 2 inches  of  vegetable  soil  had  accumu- 
lated.” Between  the  loess  and  the  mould 
there  was  a layer  from  3 to  6 inches  in  thick- 
ness, consisting  of  “ cores,  implements,  flakes, 
and  chips,  all  manufactured  from  hard  basaltic 
rock.”  It  is  therefore  probable  that  the  abo- 
rigines, at  some  former  period,  had  left  these 
objects  on  the  surface,  and  that  they  had  after- 
wards been  slowly  covered  up  by  the  castings 
of  worms. 

Farmers  in  England  are  well  aware  that 
objects  of  all  kinds,  left  on  the  surface  of  pas- 
ture-land, after  a time  disappear,  or,  as  they 
say,  work  themselves  downwards.  How  pow- 
dered lime,  cinders,  and  heavy  stones,  can  work 
down,  and  at  the  same  rate,  through  the  mat- 
ted roots  of  a grass-covered  surface,  is  a ques- 

*“  Trans,  of  the  New  Zealand  Institute,”  vol.  xii.,  1880, 
p.  152. 


ISO 


GREAT  STONES 


Chap.  III. 


tion  which  has  probably  never  occurred  to 
them.* 

The  Sinking  of  great  Stones  through  the  Ac- 
tion of  Worms . — When  a stone  of  large  size  and 
of  irregular  shape  is  left  on  the  surface  of  the 
ground,  it  rests,  of  course,  on  the  more  protu- 
berant parts;  but  worms  soon  fill  up  with  their 
castings  all  the  hollow  spaces  ‘on  the  lower 
side;  for,  as  Hensen  remarks,  they  like  the 
shelter  of  stones.  As  soon  as  the  hollows  are 
filled  up,  the  worms  eject  the  earth  which  they 
have  swallowed  beyond  the  circumference  of 
the  stones;  and  thus  the  surface  of  the  ground 
is  raised  all  round  the  stone.  As  the  burrows 
excavated  directly  beneath  the  stone  after  a 
time  collapse,  the  stone  sinks  a little. f 

* Mr.  Lindsay  Carnagie,  in  a letter  (June,  1838)  to  Sir  C.  Lyell, 
remarks  that  .Scotch  farmers  are  afraid  of  putting  lime  on 
ploughed  land  until  just  before  it  is  laid  down  for  pasture,  from 
a belief  that  it  has  some  tendency  to  sink.  He  adds  : “ Some 
years  since,  in  autumn,  I laid  lime  on  an  oat-stubble  and  ploughed 
it  down  ; thus  bringing  it  into  immediate  contact  with  the  dead 
vegetable  matter,  and  securing  its  thorough  mixture  through  the 
means  of  all  the  subsequent  operations  of  fallow.  In  consequence 
of  the  above  prejudice,  I was  considered  to  have  committed  a 
great  fault ; but  the  result  was  eminently  successful,  and  the 
practice  was  partially  followed.  By  means  of  Mr.  Darwin’s 
observations,  I think  the  prejudice  will  be  removed.” 

f This  conclusion,  which,  as  we  shall  immediately  see,  is  fully 


Chap.  III.  UNDERMINED  BY  WORMS.  15 1 

Hence  is  is,  that  boulders  which  at  some  an- 
cient period  have  rolled  down  from  a rocky 
mountain  or  cliff  on  to  a meadow  at  its  base, 
are  always  somewhat  embedded  in  the  soil; 
and,  when  removed,  leave  an  exact  impression 
of  their  lower  surfaces  in  the  under-lying  fine 
mould.  If,  however,  a boulder  is  of  such  huge 
dimensions,  that  the  earth  beneath  is  kept  dry, 
such  earth  will  not  be  inhabited  by  worms,  and 
the  boulder  will  not  sink  into  the  ground. 

A lime-kiln  formerly  stood  in  a grass-field 
near  Leith  Hill  Place  in  Surrey,  and  was  pulled 
down  35  years  before  my  visit;  all  the  loose 
rubbish  had  been  carted  away,  excepting  three 
large  stones  of  quartzose  sandstone,  which  it 
was  thought  might  hereafter  be  of  some  use. 
An  old  workman  remembered  that  they  had 
been  left  on  a bare  surface  of  broken  bricks  and 
mortar,  close  to  the  foundations  of  the  kiln; 
but  the  whole  surrounding  surface  is  now  cov- 
ered with  turf  and  mould.  The  two  largest  of 
these  stones  had  never  since  been  moved;  nor 

justified,  is  of  some  little  importance,  as  the  so-called  bench-stones, 
which  surveyors  fix  in  the  ground  as  a record  of  their  levels, 
may  in  time  become  false  standards.  My  son  Horace  intends  at 
some  future  period  to  ascertain  how  far  this  has  occurred. 


152 


GREAT  STONES 


Chap.  III. 


could  this  easily  have  been  done,  as,  when  I 
had  them  removed,  it  was  the  work  of  two  men 
with  levers.  One  of  these  stones,  and  not  the 
largest,  was  64  inches  long,  17  inches  broad, 
and  from  9 to  10  inches  in  thickness.  Its 
lower  surface  was  somewhat  protuberant  in 
the  middle;  and  this  part  still  rested  on  broken 
bricks  and  mortar,  showing  the  truth  of  the 
old  workman’s  account.  Beneath  the  brick 
rubbish  the  natural  sandy  soil,  full  of  fragments 
of  sandstone  was  found;  and  this  could  have 
yielded  very  little,  if  at  all,  to  the  weight  of  the 
stone,  as  might  have  been  expected  if  the  sub- 
soil had  been  clay.  The  surface  of  the  field, 
for  a distance  of  about  9 inches  round  the 
stone,  gradually  sloped  up  to  it,  and  close  to 
the  stone  stood  in  most  places  about  4 inches 
above  the  surrounding  ground.  The  base  of 
the  stone  was  buried  from  1 to  2 inches  be- 
neath the  general  level,  and  the  upper  surface 
projected  about  8 inches  above  this  level,  or 
about  4 inches  above  the  sloping  border  of 
turf.  After  the  removal  of  the  stone  it  became 
evident  that  one  of  its  pointed  ends  must  at 
first  have  stood  clear  above  the  ground  by 


Chap.  III.  UNDERMINED  BY  WORMS. 


153 


some  inches,  but  its  upper  surface  was  now 
on  a level  with  the  surrounding  turf.  When 
the  stone  was  removed,  an  exact  cast  of  its 
lower  side,  forming  a shallow  crateriform  hol- 
low, was  left,  the  inner  surface  of  which  con- 
sisted of  fine  black  mould,  excepting  where 
the  more  protuberant  parts  rested  on  the 
brick-rubbish.  A transverse  section  of  this 


Fig.  6. — Transverse  section  across  a large  stone,  which  had  lain 
on  a grass-field  for  35  years.  A A,  general  level  of  the 
field.  The  underlying  brick  rubbish  has  not  been  repre- 
sented. Scale  $ inch  to  one  foot. 

stone,  together  with  its  bed,  drawn  from 
measurements  made  after  it  had  been  displaced, 
is  here  given  on  a scale  of  ^ inch  to  a foot  (Fig. 
6).  The  turf-covered  border  which  sloped  up 
to  the  stone,  consisted  of  fine  vegetable 
mould,  in  one  part  7 inches  in  thickness. 
This  evidently  consisted  of  worm-castings, 
several  of  which  had  been  recently  ejected. 


154 


GREAT  STONES 


Chap.  III. 


The  whole  stone  had  sunk  in  the  thirty-five 
years,  as  far  as  I could  judge,  about  inch; 
and  this  must  have  been  due  to  the  brick-rub- 
bish beneath  the  more  protuberant  parts  hav- 
ing been  undermined  by  worms.  At  this  rate 
the  upper  surface  of  the  stone,  if  it  had  been 
left  undisturbed,  would  have  sunk  to  the  gen- 
eral level  of  the  field  in  247  years;  but  before 
this  could  have  occurred,  some  earth  would 
have  been  washed  down  by  heavy  rain  from 
the  castings  on  the  raised  border  of  turf  oyer 
the  upper  surface  of  the  stone. 

The  second  stone  was  larger  than  the  one 
just  described,  viz.,  67  inches  in  length,  39  in 
breadth,  and  15  in  thickness.  The  lower  sur- 
face was  nearly  flat,  so  that  the  worms  must 
soon  have  been  compelled  to  eject  their  cast- 
ings beyond  its  circumference.  The  stone  as 
a whole  had  sunk  about  2 inches  into  the 
ground.  At  this  rate  it  would  have  required 
262  years  for  its  upper  surface  to  have  sunk 
to  the  general  level  of  the  field.  The  up- 
wardly sloping,  turf-covered  border  round  the 
stone  was  broader  than  in  the  last  case,  viz., 
from  14  to  16  inches;  and  why  this  should  be 


Chap.  III.  UNDERMINED  BY  WORMS. 


155 


so,  I could  see  no  reason.  In  most  parts  this 
border  was  not  so  high  as  in  the  last  case,  viz., 
from  2 to  2\  inches,  but  in  one  place  it  was  as 
much  as  5J.  Its  average  height  close  to  the 
stone  was  probably  about  3 inches,  and  it 
thinned  out  to  nothing.  If  so,  a layer  of  fine 
earth,  15  inches  in  breadth  and  i-|  inch  in  aver- 
age thickness,  of  sufficient  length  to  surround 
the  whole  of  the  much  elongated  slab,  must 
have  been  brought  up  by  the  worms  in  chief 
part  from  beneath  the  stone  in  the  course  of  35 
years.  This  amount  would  be  amply  suffi- 
cient to  account  for  its  having  sunk  about  2 
inches  into  the  ground;  more  especially  if  we 
bear  in  mind  that  a good  deal  of  the  finest 
earth  would  have  been  washed  by  heavy  rain 
from  the  castings  ejected  on  the  sloping  bor- 
der down  to  the  level  of  the  field.  Some  fresh 
castings  were  seen  close  to  the  stone.  Never- 
theless, on  digging  a large  hole  to  a depth  of 
18  inches  where  the  stone  had  lain,  only  two 
worms  and  a few  burrows  were  seen,  although 
the  soil  was  damp  and  seemed  favourable  for 
worms.  There  were  some  large  colonies  of 
ants  beneath  the  stone,  and  possibly  since 


Chap.  III. 


156  GREAT  STONES 

their  establishment  the  worms  had  decreased 
in  number. 

The  third  stone  was  only  about  half  as 
large  as  the  others;  and  two  strong  boys 
could  together  have  rolled  it  over.  I have 
no  doubt  that  it  had  been  rolled  over  at  a mod- 
erately recent  time,  for  it  now  lay  at  some  dis- 
tance from  the  other  two  stones  at  the  bottom 
of  a little  adjoining  slope.  It  rested  also  on 
fine  earth,  instead  of  partly  on  brick-rubbish. 
In  agreement  with  this  conclusion,  the  raised 
surrounding  border  of  turf  was  only  1 inch 
high  in  some  parts,  and  2 inches  in  other 
parts.  There  were  no  colonies  of  ants  be- 
neath this  stone,  and  on  digging  a hole  where 
it  had  lain,  several  burrows  and  worms  were 
found. 

At  Stonehenge,  some  of  the  outer  Druidi- 
cal  stones  are  now  prostrate,  having  fallen  at 
a remote  but  unknown  period;  and  these  have 
become  buried  to  a moderate  depth  in  the 
ground.  They  are  surrounded  by  sloping  bor- 
ders of  turf,  on  which  recent  castings  were 
seen.  Close  to  one  of  these  fallen  stones, 
which  was  17  ft.  long,  6 ft.  broad,  and  2&§ 


Chap.  III.  UNDERMINED  BY  WORMS. 


157 


inches  thick,  a hole  was  dug;  and  here  the 
vegetable  mould  was  at  least  9^  inches  in 
thickness.  At  this  depth  a flint  was  found, 
and  a little  higher  up  on  one  side  of  the  hole 
a fragment  of  glass.  The  base  of  the  stone 
lay  about  9J  inches  beneath  the  level  of  the 
surrounding  ground,  and  its  upper  surface  19 
inches  above  the  ground. 

A hole  was  also  dug  close  to  a second  huge 
stone,  which  in  falling  had  broken  into  two 
pieces;  and  this  must  have  happened  long 
ago,  judging  from  the  weathered  aspect  of 
the  fractured  ends.  The  base  was  buried  to 
a depth  of  10  inches,  as  was  ascertained  by 
driving  an  iron  skewer  horizontally  into  the 
ground  beneath  it.  The  vegetable  mould 
forming  the  turf-covered  sloping  border  round 
the  stone,  on  which  many  castings  had  re- 
cently been  ejected,  was  10  inches  in  thick- 
ness; and  most  of  this  mould  must  have  been 
brought  up  by  worms  from  beneath  its  base. 
At  a distance  of  8 yards  from  the  stone,  the 
mould  was  only  5!  inches  in  thickness  (with  a 
piece  of  tobacco  pipe  at  a depth  of  4 inches), 
and  this  rested  on  broken  flint  and  chalk 


x58 


GREAT  STONES 


Chap.  III. 


which  could  not  have  easily  yielded  to  the 
pressure  or  weight  of  the  stone. 

A straight  rod  was  fixed  horizontally  (by 
the  aid  of  a spirit-level)  across  a third  fallen 
stone,  which  was  7 feet  9 inches  long;  and  the 
contour  of  the  projecting  parts  and  of  the  ad- 


Fig.  7. — Section  through  one  of  the  fallen  Druidical  stones  at 
Stonehenge,  showing  how  much  it  had  sunk  into  the  ground. 
Scale  i inch  to  one  foot. 


joining  ground,  which  was  not  quite  level, 
was  thus  ascertained,  as  shown  in  the  accom- 
panying diagram  (Fig.  7)  on  a scale  of  inch 
to  a foot.  The  turf-covered  border  sloped  up 
to  the  stone  on  one  side  to  a height  of  4 
inches,  and  on  the  opposite  side  to  only  2\ 
inches  above  the  general  level.  A hole  was 
dug  on  the  eastern  side,  and  the  base  of  the 
stone  was  here  found  to  lie  at  a depth  of  4 
inches  beneath  the  general  level  of  the  ground, 


Chap.  III.  UNDERMINED  BY  WORMS. 


159 

and  of  8 inches  beneath  the  top  of  the  sloping 
turf-covered  border. 

Sufficient  evidence  has  now  been  given 
showing  that  small  objects  left  on  the  surface 
of  the  land  where  worms  abound  soon  get 
buried,  and  that  large  stones  sink  slowly 
downwards  through  the  same  means.  Every 
step  of  the  process  could  be  followed,  from 
the  accidental  deposition  of  a single  casting 
on  a small  object  lying  loose  on  the  surface, 
to  its  being  entangled  amidst  the  matted 
roots  of  the  turf,  and  lastly  to  its  being  em- 
bedded in  the  mould  at  various  depths  be- 
neath the  surface.  When  the  same  field  was 
re-examined  after  the  interval  of  a few  years, 
such  objects  were  found  at  a greater  depth 
than  before.  The  straightness  and  regularity 
of  the  lines  formed  by  the  embedded  objects, 
and  their  parallelism  with  the  surface  of  the 
land,  are  the  most  striking  features  of  the  case-; 
for  this  parallelism  shows  how  equably  the 
worms  must  have  worked;  the  result  being, 
however,  partly  the  effect  of  the  washing 
down  of  the  fresh  castings  by  rain.  The  spe- 


i6o 


NUMBER  OF  WORMS. 


Chap.  III. 


cific  gravity  of  the  objects  does  not  affect 
their  rate  of  sinking,  as  could  be  seen  by  por- 
ous cinders,  burnt  marl,  chalk  and  quartz  peb- 
bles, having  all  sunk  to  the  same  depth  within 
the  same  time.  Considering  the  nature  of  the 
substratum,  which  at  Leith  Hill  Place  was 
sandy  soil  including  many  bits  of  rock,  and  at 
Stonehenge,  chalk-rubble  with  broken  flints; 
considering,  also,  the  presence  of  the  turf-cov- 
ered sloping  border  of  mould  round  the  great 
fragments  of  stone  at  both  these  places,  their 
sinking  does  not  appear  to  have  been  sensibly 
aided  by  their  weight,  though  this  was  consid- 
erable.* 

On  the  number  of  worms  which  live  within  a 
given  space. — We  will  now  show,  firstly,  what 
a vast  number  of  worms  live  unseen  by  us  be- 
neath our  feet,  and,  secondly,  the  actual 
weight  of  the  earth  which  they  bring  up  to 

* Mr.  R.  Mallet  remarks  (“  Quarterly  Journal  of  Geolog.  Soc.,” 
vol.  xxxiii.,  1877,  p.  745)  that  “the  extent  to  which  the  ground 
beneath  the  foundations  of  ponderous  architectural  structures, 
such  as  cathedral  towers,  has  been  known  to  become  compressed, 
is  as  remarkable  as  it  is  instructive  and  curious.  The  amount 
of  depression  in  some  cases  may  be  measured  by  feet.”  He 
instances  the  Tower  of  Pisa,  but  adds  that  it  was  founded  on 
“ dense  clay.” 


Chap.  III. 


NUMBER  OF  WORMS. 


161 


the  surface  within  a given  space  and  within  a 
given  time.  Hensen,  who  has  published  so 
full  and  interesting  an  account  of  the  habits 
of  worms,*  calculates,  from  the  number  which 
he  found  in  a measured  space,  that  there  must 
exist  133,000  living  worms  in  a hectare  of 
land,  or  53,767  in  an  acre.  This  latter  num- 
ber of  worms  would  weigh  356  pounds,  taking 
Hensen’s  standard  of  the  weight  of  a single 
worm,  namely,  one  gram.  It  should,  how- 
ever, be  noted  that  this  calculation  is  founded 
on  the  numbers  found  in  a garden,  and  Hen- 
sen  believes  that  worms  are  here  twice  as  nu- 
merous as  in  corn-fields.  The  above  result,  as- 
tonishing though  it  be,  seems  to  me  credible, 
judging  from  the  number  of  worms  which  I 
have  sometimes  seen,  and  from  the  number 
daily  destroyed  by  birds  without  the  species 
being  exterminated.  Some  barrels  of  bad  ale 
were  left  on  Mr.  Miller's  land,f  in  the  hope  of 
making  vinegar,  but  the  vinegar  proved  bad, 
and  the  barrels  were  upset.  It  should  be  prem- 

* “Zeitschrift  fur  wissensch.  Zoolog.,”  Bd.  xxviii.,  1877,  p. 
354. 

f See  Mr.  Dancer’s  paper  in  “ Proc.  Phil.  Soc.  of  Manches- 
ter,” 1877,  p.  248. 


162  WEIGHT  OF  EARTH  Chap.  III. 

ised  that  acetic  acid  is  so  deadly  a poison  to 
worms  that  Perrier  found  that  a glass  rod 
dipped  into  this  acid  and  then  into  a consider- 
able body  of  water  in  which  worms  were  im- 
mersed, invariably  killed  them  quickly.  On 
the  morning  after  the  barrels  had  been  upset, 
“ the  heaps  of  worms  which  lay  dead  on  the 
ground  were  so  amazing,  that  if  Mr.  Miller  had 
not  seen  them,  he  could  not  have  thought  it 
possible  for  such  numbers  to  have  existed  in 
the  space.”  As  further  evidence  of  the  large 
number  of  worms  which  live  in  the  ground, 
Hensen  states  that  he  found  in  a garden  sixty- 
four  open  burrows  in  a space  of  14^  square 
feet,  that  is,  nine  in  2 square  feet.  But  the 
burrows  are  sometimes  much  more  numerous, 
for  when  digging  in  a grass-field  near  Maer 
Hall,  I found  a cake  of  dry  earth,  as  large  as 
my  two  open  hands,  which  was  penetrated  by 
seven  burrows,  as  large  as  goose-quills. 

Weight  of  the  earth  ejected  from  a single 
burrow,  and  from  all  the  burrows  within  a given 
space. — With  respect  to  the  weight  of  the 
earth  daily  ejected  by  worms,  Hensen  found 
that  it  amounted,  in  the  case  of  some  worms 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


163 


which  he  kept  in  confinement,  and  which  he 
appears  to  have  fed  with  leaves,  to  only  0.5 
gram,  or  less  than  8 grains  per  diem.  But  a 
very  much  larger  amount  must  be  ejected  by 
worms  in  their  natural  state,  at  the  periods 
when  they  consume  earth  as  food  instead  of 
leaves,  and  when  they  are  making  deep  bur- 
rows. This  is  rendered  almost  certain  by  the 
following  weights  of  the  castings  thrown  up  at 
the  mouths  of  single  burrows;  the  whole  of 
which  appeared  to  have  been  ejected  within  no 
long  time,  as  was  certainly  the  case  in  several 
instances.  The  castings  were  dried  (excepting 
in  one  specified  instance)  by  exposure  during 
many  days  to  the  sun  or  before  a hot  fire. 


Weight  of  the  Castings  accumulated  at  the  Mouth 
of  a Single  Burrow. 


(1.)  Down,  Kent  (sub-soil  red  clay,  full  of  flints,  overly-  ' 
ing  the  chalk). — The  largest  casting  which  I could 
find  on  the  flanks  of  a steep  valley,  the  sub-soil  being  V 
here  shallow.  In  this  one  case,  the  casting  was  not 
well  dried 

(2.)  Down. — Largest  casting  which  I could  find  (con-  ' 
sisting  chiefly  of  calcareous  matter),  on  extremely  I 
poor  pasture  land  at  the  bottom  of  the  valley  men-  ‘ 
tioned  under  (i.) 

(3.)  Down. — A large  casting,  but  not  of  unusual  size,  i 
from  a nearly  level  field,  poor  pasture,  laid  down  in 
grass  about  35  years  before  . . . . . . . . j 

(4.)  Down. — Average  weight  of  11  not  large  castings 
ejected  on  a sloping  surface  on  my  lawn,  after  they  I 
had  suffered  some  loss  of  weight  from  being  exposed  j 
during  a considerable  length  of  time  to  rain  . . J 


Ounces. 

3.98 


3-87 


1.22 


0.7 


164 


WEIGHT  OF  EARTH 


Chap.  III. 


Weight  of  the  Castings  accumulated  at  the  Mouth 
of  A Single  Burrow — continued. 


(5.)  Near  Nice  in  France. — Average  weight  of  12  cast-" 
ings  of  ordinary  dimensions,  collected  by  Dr.  King 
on  land  which  had  not  been  mown  for  a long  time 
and  where  worms  abounded,  viz.,  a lawn  protected 
by  shrubberies,  near  the  sea  : soil  sandy  and  calcare-  - 
ous  ; these  castings  had  been  exposed  for  some  time 
to  rain,  before  being  collected,  and  must  have  lost 
some  weight  by  disintegration,  but  they  still  retained 
their  form  . . . . . . . . . . . . 

(6.)  The  heaviest  of  the  above  twelve  castings 
(7.)  Lower  Bengal. — Average  weight  of  22  castings,  ) 
collected  by  Mr.  J.  Scott,  and  stated  by  him  to  have  >• 
been  thrown  up  in  the  course  of  one  or  two  nights  ) 
(8.)  The  heaviest  of  the  above  22  castings 
(9.)  Nilgiri  Mountains,  S.  India;  average  weight  of  the") 
5 largest  castings  collected  by  Dr.  King.  They  had  ( 
been  exposed  to  the  rain  of  the  last  monsoon,  and  | 
must  have  lost  some  weight  . . . . . . . . J 

(10.)  The  heaviest  of  the  above  5 castings 


Ounces. 


i-37 


1.76 

1.24 

2.09 

3- i5 

4- 34 


In  this  table  we  see  that  castings  which 
had  been  ejected  at  the  mouth  of  the  same 
burrow,  and  which  in  most  cases  appeared 
fresh  and  always  retained  their  vermiform 
configuration,  generally  exceeded  an  ounce  in 
weight  after  being  dried,  and  sometimes  nearly 
equalled  a quarter  of  a pound.  On  the  Nil- 
giri mountains  one  casting  even  exceeded  this 
latter  weight.  The  largest  castings  in  Eng- 
land were  found  on  extremely  poor  pasture- 
land;  and  these,  as  far  as  I have  seen,  are  gen- 
erally larger  than  those  on  land  producing  a 
rich  vegetation.  It  would  appear  that  worms 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


165 

have  to  swallow  a greater  amount  of  earth  on 
poor  than  on  rich  land,  in  order  to  obtain  suffi- 
cient nutriment. 

With  respect  to  the  tower-like  castings 
near  Nice  (Nos.  5 and  6 in  the  above  table), 
Dr.  King  often  found  five  or  six  of  them  on  a 
square  foot  of  surface;  and  these,  judging 
from  their  average  weight,  would  have 
weighed  together  ounces;  so  that  the 
weight  of  those  on  a square  yard  would  have 
been  4 lb.  3^  oz.  Dr.  King  collected,  near  the 
close  of  the  year  1872,  all  the  castings  which 
still  retained  their  vermiform  shape,  whether 
broken  down  or  not,  from  a square  foot,  in  a 
place  abounding  with  worms,  on  the  summit 
of  a bank,  where  no  castings  could  have  rolled 
down  from  above.  These  castings  must  have 
been  ejected,  as  he  judged  from  their  appear- 
ance in  reference  to  the  rainy  and  dry  periods 
near  Nice,  within  the  previous  five  or  six 
months;  they  weighed  9J  oz.,  or  5 lb.  5J  oz. 
per  square  yard.  After  an  interval  of  four 
months  Dr.  King  collected  all  the  castings  sub- 
sequently ejected  on  the  same  square  foot  of 
surface,  and  they  weighed  2-J  oz.,  or  1 lb.  6J  oz. 


1 66  WEIGHT  OF  EARTH  Chap.  III. 

per  square  yard.  Therefore  within  about  ten 
months,  or  we  will  say  for  safety’s  sake  within 
a year,  12  oz.  of  castings  were  thrown  up  on 
this  one  square  foot,  or  6.75  pounds  on  the 
square  yard;  and  this  would  give  14.58  tons 
per  acre. 

In  a field  at  the  bottom  of  a valley  in  the 
chalk  (see  No.  2 in  the  foregoing  table),  a 
square  yard  was  measured  at  a spot  where 
very  large  castings  abounded;  they  appeared, 
however,  almost  equally  numerous  in  a few 
other  places.  These  castings,  which  retained 
perfectly  their  vermiform  shape,  were  col- 
lected; and  they  weighed  when  partially  dried, 
1 lb.  13^  oz.  This  field  had  been  rolled  with 
a heavy  agricultural  roller  fifty-two  days  be- 
fore, and  this  would  certainly  have  flattened 
every  single  casting  on  the  land.  The  weather 
had  been  very  dry  for  two  or  three  weeks  before 
the  day  of  collection,  so  that  not  one  casting 
appeared  fresh  or  had  been  recently  ejected. 
We  may  therefore  assume  that  those  which 
were  weighed  had  been  ejected  within,  we  will 
say,  forty  days  from  the  time  when  the  field 
was  rolled, — that  is,  twelve  days  short  of  the 


Chap.  III.  BROUGHT  UP  BY  WORMS.  167 

whole  intervening  period.  I had  examined  the 
same  part  of  the  field  shortly  before  it  was 
rolled,  and  it  then  abounded  with  fresh  cast- 
ings. Worms  do  not  work  in  dry  weather 
during  the  summer,  or  in  winter  during  severe 
frosts.  If  we  assume  that  they  work  for  only 
half  the  year — though  this  is  too  low  an  esti- 
mate-then the  worms  in  this  field  would 
eject  during  the  year,  8.387  pounds  per  square 
yard;  or  18.12  tons  per  acre,  assuming  the 
whole  surface  to  be  equally  productive  in  cast- 
ings. 

In  the  foregoing  cases  some  of  the  neces- 
sary data  had  to  be  estimated,  but  in  the  two 
following  cases  the  results  are  much  more 
trustworthy.  A lady,  on  whose  accuracy  I 
can  implicitly  rely,  offered  to  collect  during  a 
year  all  the  castings  thrown  up  on  two  sepa- 
rate square  yards,  near  Leith  Hill  Place,  in 
Surrey.  The  amount  collected  was,  however, 
somewhat  less  than  that  originally  ejected  by 
the  worms;  for,  as  I have  repeatedly  observed, 
a good  deal  of  the  finest  earth  is  washed  away, 
whenever  castings  are  thrown  up  during  or 
shortly  before  heavy  rain.  Small  portions 


1 68  WEIGHT  OF  EARTH  Chap.  III. 

also  adhered  to  the  surrounding  blades  of 
grass,  and  it  required  too  much  time  to  detach 
every  one  of  them.  On  sandy  soil,  as  in  the 
present  instance,  castings  are  liable  to  crumble 
after  dry  weather,  and  particles  were  thus 
often  lost.  The  lady  also  occasionally  left 
home  for  a week  or  two,  and  at  such  times  the 
castings  must  have  suffered  still  greater  loss 
from  exposure  to  the  weather.  These  losses 
were,  however,  compensated  to  some  extent 
by  the  collections  having  been  made  on  one  of 
the  squares  for  four  days,  and  on  the  other 
square  for  two  days  more  than  the  year. 

A space  was  selected  (October  9th,  1870) 
on  a broad,  grass-covered  terrace,  which  had 
been  mowed  and  swept  during  many  years. 
It  faced  the  south,  but  was  shaded  during  part 
of  the  day  by  trees.  It  had  been  formed  at 
least  a century  ago  by  a great  accumulation 
of  small  and  large  fragments  of  sandstone, 
together  with  some  sandy  earth,  rammed 
down  level.  It  is  probable  that  it  was  at 
first  protected  by  being  covered  with  turf. 
This  terrace,  judging  from  the  number  of  cast- 
ings on  it,  was  rather  unfavourable  for  the  ex- 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


169 


istence  of  worms,  in  comparison  with  the 
neighbouring  fields  and  an  upper  terrace.  It 
was  indeed  surprising  that  as  many  worms 
could  live  here  as  were  seen;  for  on  digging 
a hole  in  this  terrace,  the  black  vegetable 
mould  together  with  the  turf  was  only  four 
inches  in  thickness,  beneath  which  lay  the 
level  surface  of  light-coloured  sandy  soil,  with 
many  fragments  of  sandstone.  Before  any 
castings  were  collected  all  the  previously  ex- 
isting ones  were  carefully  removed.  The 
last  day’s  collection  was  on  October  14th, 
1871.  The  castings  were  then  well  dried 
before  a fire;  and  they  weighed  exactly  3!  lbs. 
This  would  give  for  an  acre  of  similar  land 
7.56  tons  of  dry  earth  annually  ejected  by 
worms. 

The  second  square  was  marked  on  unen- 
closed common  land,  at  a height  of  about 
700  ft.  above  the  sea,  at  some  little  distance 
from  Leith  Hill  Tower.  The  surface  was 
clothed  with  short,  fine  turf,  and  had  never 
been  disturbed  by  the  hand  of  man.  The  spot 
selected  appeared  neither  particularly  favour- 
able nor  the  reverse  for  worms;  but  I have 
12 


170  WEIGHT  OF  EARTH  Chap.  III. 

often  noticed  that  castings  are  especially 
abundant  on  common  land,  and  this  may,  per- 
haps, be  attributed  to  the  poorness  of  the  soil. 
The  vegetable  mould  was  here  between  three 
and  four  inches  in  thickness.  As  this  spot 
was  at  some  distance  from  the  house  where 
the  lady  lived,  the  castings  were  not  collected 
at  such  short  intervals  of  time  as  those  on  the 
Terrace;  consequently  the  loss  of  fine  earth 
during  rainy  weather  must  have  been  greater 
in  this  than  in  the  last  case.  The  castings 
moreover  were  more  sandy,  and  in  collecting 
them  during  dry  weather  they  sometimes 
crumbled  into  dust,  and  much  was  thus  lost. 
Therefore  it  is  certain  that  the  worms  brought 
up  to  the  surface  considerably  more  earth 
than  that  which  was  collected.  The  last  col- 
lection was  made  on  October  27th,  1871 ; i.  e., 
367  days  after  the  square  had  been  marked 
out  and  the  surface  cleared  of  all  pre-existing 
castings.  The  collected  castings,  after 
being  well  dried,  weighed  7.453  pounds; 
and  this  would  give,  for  an  acre  of  the  same 
kind  of  land,  16.1  tons  of  annually  ejected  dry 
earth. 


Chap.  III.  BROUGHT  UP  BY  WORMS. 


171 


Summary  of  the  Four  Foregoing  Cases. 

(1.)  Castings  ejected  near  Nice  within  about  a year,  collected 
by  Dr.  King  on  a square  foot  of  surface,  calculated  to  yield  per 
acre  14.58  tons. 

(2.)  Castings  ejected  during  about  45  days  on  a square 
yard,  in  a field  of  poor  pasture  at  the  bottom  of  a large 
valley  in  the  Chalk,  calculated  to  yield  annually  per  acre 
18.12  tons. 

(3.)  Castings  collected  from  a square  yard  on  an  old  ter- 
race at  Leith  Hill  Place,  during  369  days,  calculated  to  yield 
annually  per  acre  7.56  tons. 

(4.)  Castings  collected  from  a square  yard  on  Leith  Hill 
Common  during  367  days,  calculated  to  yield  annually  per  acre 
16. 1 tons. 


The  thickness  of  the  layer  of  mould , which 
castings  ejected  during  a year  would  form  if  uni- 
formly spread  out . — As  we  know  from  the  last 
two  cases  in  the  above  summary,  the  weight  of 
the  dried  castings  ejected  by  worms  during  a 
year  on  a square  yard  of  surface,  I wished  to 
learn  how  thick  a layer  of  ordinary  mould  this 
amount  would  form  if  spread  uniformly  over 
a square  yard.  The  dry  castings  were  there- 
fore broken  into  small  particles,  and  whilst  be- 
ing placed  in  a measure  were  well  shaken  and 
pressed  down.  Those  collected  on  the  Ter- 
race amounted  to  124.77  cubic  inches;  and 
this  amount,  if  spread  out  over  a square  yard, 


172 


THICKNESS  OF  THE  MOULD  Chap.  III. 


would  make  a layer  .09612  inch  in  thickness. 
Those  collected  on  the  Common  amounted  to 
197.56  cubic  inches,  and  would  make  a similar 
layer  .1524  inch  in  thickness. 

These  thicknesses  must,  however,  be  cor- 
rected, for  the  triturated  castings,  after  being 
well  shaken  down  and  pressed,  did  not  make 
nearly  so  compact  a mass  as  vegetable  mould, 
though  each  separate  particle  was  very  com- 
pact. Yet  mould  is  far  from  being  compact, 
as  is  shown  by  the  number  of  air-bubbles 
which  rise  up  when  the  surface  is  flooded  with 
water.  It  is  moreover  penetrated  by  many 
fine  roots.  To  ascertain  approximately  by 
how  much  ordinary  vegetable  mould  would  be 
increased  in  bulk  by  being  broken  up  into 
small  particles  and  then  dried,  a thin  oblong- 
block  of  somewhat  argillaceous  mould  (with 
the  turf  pared  off)  was  measured  before  being 
broken  up,  was  well  dried  and  again  measured. 
The  drying  caused  it  to  shrink  by  -y  of  its 
original  bulk,  judging  from  exterior  measure- 
ments alone.  It  was  then  triturated  and  part- 
ly reduced  to  powder,  in  the  same  manner  as 
the  castings  had  been  treated,  and  its  bulk 


Chap.  III.  ANNUALLY  ACCUMULATED. 


173 


now  exceeded  (notwithstanding  shrinkage 
from  drying)  by  -jV  that  of  the  original  block 
of  damp  mould.  Therefore  the  above  calcu- 
lated thickness  of  the  layer,  formed  by  the 
castings  from  the  Terrace,  after  being  damped 
and  spread  over  a square  yard,  would  have  to 
be  reduced  by  and  this  will  reduce  the 
layer  to  .09  of  an  inch,  so  that  a layer  .9  inch 
in  thickness  would  be  formed  in  the  course  of 
ten  years.  On  the  same  principle  the  castings 
from  the  Common  would  make  in  the  course 
of  a single  year  a layer  .1429  inch,  or  in  the 
course  of  10  years  1.429  inch,  in  thickness. 
We  may  say  in  round  numbers  that  the  thick- 
ness in  the  former  case  would  amount  to  near- 
ly 1 inch,  and  in  the  second  case  to  nearly  1^ 
inch  in  10  years. 

In  order  to  compare  these  results  with 
those  deduced  from  the  rates  at  which  small 
objects  left  on  the  surfaces  of  grass  fields  be- 
come buried  (as  described  in  the  early  part  of 
this  chapter),  we  will  give  the  following  sum- 
mary : — 


174 


THICKNESS  OF  THE  MOULD  Chap.  III. 


Summary  of  the  Thickness  of  the  Mould  accumulated 
over  Objects  left  strewed  on  the  Surface,  in  the 
Course  of  Ten  Years. 

The  accumulation  of  mould  during  I4f  years  on  the  surface 
of  a dry,  sandy,  grass-field  near  Maer  Hall,  amounted  to  2.2 
inches  in  10  years. 

The  accumulation  during  2I-J  years  on  a swampy  field  near 
Maer  Hall,  amounted  to  nearly  1.9  inch  in  10  years. 

The  accumulation  during  7 years  on  a very  swampy  field  near 
Maer  Hall  amounted  to  2.1  inches  in  10  years. 

The  accumulation  during  29  years,  on  good,  argillaceous 
pasture-land  over  the  Chalk  at  Down,  amounted  to  2.2  inches  in 
10  years. 

The  accumulation  during  30  years  on  the  side  of  a valley  over 
the  Chalk  at  Down,  the  soil  being  argillaceous,  very  poor,  and 
only  just  converted  into  pasture  (so  that  it  was  for  some  years 
unfavourable  for  worms),  amounted  to  0.83  inches  in  10  years. 

In  these  cases  (excepting  the  last)  it  may 
be  seen  that  the  amount  of  earth  brought 
to  the  surface  during  io  years  is  somewhat 
greater  than  that  calculated  from  the  castings 
which  were  actually  weighed.  This  excess 
may  be  partly  accounted  for  by  the  loss  which 
the  weighed  castings  had  previously  under- 
gone through  being  washed  by  rain,  by  the 
adhesion  of  particles  to  the  blades  of  the  sur- 
rounding grass,  and  by  their  crumbling  when 
dry.  Nor  must  we  overlook  other  agencies 
which  in  all  ordinary  cases  add  to  the  amount 
of  mould,  and  which  would  not  be  included  in 


Chap.  III.  ANNUALLY  ACCUMULATED. 


175 


the  castings  that  were  collected,  namely,  the 
fine  earth  brought  up  to  the  surface  by  burrow- 
ing larvae  and  insects,  especially  by  ants.  The 
earth  brought  up  by  moles  generally  has  a 
somewhat  different  appearance  from  vegeta- 
ble mould;  but  after  a time  would  not  be  dis- 
tinguishable from  it.  In  dry  countries  more- 
over the  wind  plays  an  important  part  in  car- 
rying dust  from  one  place  to  another,  and 
even  in  England  it  must  add  to  the  mould  on 
fields  near  great  roads.  But  in  our  county 
these  latter  several  agencies  appear  to  be  of 
quite  subordinate  importance  in  comparison 
with  the  action  of  worms. 

We  have  no  means  of  judging  how  great  a 
weight  of  earth  a single  full-sized  worm  ejects 
during  a year.  Hensen  estimates  that  53,767 
worms  exist  in  an  acre  of  land;  but  this  is 
founded  on  the  number  found  in  gardens,  and 
he  believes  that  only  about  half  as  many  live 
in  corn-fields.  How  many  live  in  old  pasture- 
land  is  unknown;  but  if  we  assume  that  half 
the  above  number,  or  26,886  worms  live  on 
such  land,  then  taking  from  the  previous  sum- 
mary 15  tons  as  the  weight  of  the  castings  an- 


1 76  THICKNESS  OF  THE  MOULD  Chap.  III. 

nually  thrown  up  on  an  acre  of  land,  each 
worm  must  annually  eject  20  ounces.  A full- 
sized  casting  at  the  mouth  of  a single  burrow 
often  exceeds,  as  we  have  seen,  an  ounce  in 
weight;  and  it  is  probable  that  worms  eject 
more  than  twenty  full-sized  castings  during  a 
year.  If  they  eject  annually  more  than  20 
ounces,  we  may  infer  that  the  worms  which 
live  in  an  acre  of  pasture-land  must  be  less 
than  26,886  in  number. 

Worms  live  chiefly  in  the  superficial 
mould,  which  is  usually  from  4 or  5 to  10  and 
even  12  inches  in  thickness;  and  it  is  this 
mould  which  passes  over  and  over  again 
through  their  bodies  and  is  brought  to  the 
surface.  But  worms  occasionally  burrow  into 
the  sub-soil  to  a much  greater  depth,  and  on 
such  occasions  they  bring  up  earth  from  this 
greater  depth;  and  this  process  has  gone  on 
for  countless  ages.  Therefore  the  superficial 
layer  of  mould  would  ultimately  attain, 
though  at  a slower  and  slower  rate,  a thick- 
ness equal  to  the  depth  to  which  worms  ever 
burrow,  were  there  not  other  opposing  agen- 
cies at  work  which  carry  away  to  a lower  level 


Chap.  III.  ANNUALLY  ACCUMULATED. 


i/7 

some  of  the  finest  earth  which  is  continually 
being  brought  to  the  surface  by  worms.  How 
great  a thickness  vegetable  mould  ever  at- 
tains, I have  not  had  good  opportunities  for 
observing;  but  in  the  next  chapter,  when  we 
consider  the  burial  of  ancient  buildings,  some 
facts  will  be  given  on  this  head.  In  the  last 
two  chapters  we  shall  see  that  the  soil  is  actu- 
ally increased,  though  only  to  a small  degree, 
through  the  agency  of  worms;  but  their  chief 
work  is  to  sift  the  finer  from  the  coarser  parti- 
cles, to  mingle  the  whole  with  vegetable  de- 
bris, and  to  saturate  it  with  their  intestinal  se- 
cretions. 

Finally,  no  one  who  considers  the  facts 
given  in  this  chapter — on  the  burying  of  small 
objects  and  on  the  sinking  of  great  stones  left 
on  the  surface — on  the  vast  number  of  worms 
which  live  within  a moderate  extent  of  ground 
— on  the  weight  of  the  castings  ejected  from 
the  mouth  of  the  same  burrow — on  the  weight 
of  all  the  castings  ejected  within  a known  time 
on  a measured  space — will  hereafter,  as  I be- 
lieve, doubt  that  worms  play  an  important 
part  in  nature. 


CHAPTER  IV. 


THE  PART  WHICH  WORMS  HAVE  PLAYED  IN  THE 
BURIAL  OF  ANCIENT  BUILDINGS. 


The  accumulation  of  rubbish  on  the  sites  of  great  cities  inde- 
pendent of  the  action  of  worms — The  burial  of  a Roman  villa 
at  Abinger — The  floors  and  walls  penetrated  by  worms — 
Subsidence  of  a modern  pavement — The  buried  pavement  at 
Beaulieu  Abbey — Roman  villas  at  Chedworth  and  Brading — 
The  remains  of  the  Roman  town  at  Silchester — The  nature  of 
the  debris  by  which  the  remains  are  covered — The  penetration 
of  the  tessellated  floors  and  walls  by  worms — Subsidence  of 
the  floors — Thickness  of  the  mould — The  old  Roman  city  of 
Wroxeter — Thickness  of  the  mould — Depth  of  the  foundations 
of  some  of  the  buildings — Conclusion. 


Archaeologists  are  probably  not  aware 
how  much  they  owe  to  worms  for  the  preser- 
vation of  many  ancient  objects.  Coins,  gold 
ornaments,  stone  implements,  &c.,  if  dropped 
on  the  surface  of  the  ground,  will  infallibly  be 
buried  by  the  castings  of  worms  in  a few  years, 
and  will  thus  be  safely  preserved,  until  the  land 
at  some  future  time  is  turned  up.  For  in- 
stance, many  years  ago  a grass-field  was 
178 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


179 


ploughed  on  the  northern  side  of  the  Severn, 
not  far  from  Shrewsbury;  and  a surprising 
number  of  iron  arrow-heads  were  found  at  the 
bottom  of  the  furrows,  which,  as  Mr.  Blake- 
way, a local  antiquary,  believed  were  relics  of 
the  battle  of  Shrewsbury  in  the  year  1403,  and 
no  doubt  had  been  originally  left  strewed  on 
the  battle-field.  In  the  present  chapter,  I 
shall  show  that  not  only  implements,  &c.,  are 
thus  preserved,  but  that  the  floors  and  the  re- 
mains of  many  ancient  buildings  in  England 
have  been  buried  so  effectually,  in  large  part 
through  the  action  of  worms,  that  they  have 
been  discovered  in  recent  times  solely  through 
various  accidents.  The  enormous  beds  of 
rubbish,  several  yards  in  thickness,  which  un- 
derlie many  cities,  such  as  Rome,  Paris,  and 
London,  the  lower  ones  being  of  great  an- 
tiquity, are  not  here  referred  to,  as  they  have 
not  been  in  any  way  acted  on  by  worms. 
When  we  consider  how  much  matter  is  daily 
brought  into  a great  city  for  building,  fuel, 
clothing  and  food,  and  that  in  old  times  when 
the  roads  were  bad  and  the  work  of  the  scav- 
enger was  neglected,  a comparatively  small 


i8o 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


amount  was  carried  away,  we  may  agree  with 
Elie  de  Beaumont,  who,  in  discussing  this  sub- 
ject, says,  “ pour  une  voiture  de  materiaux 
“ qui  en  sort,  on  y en  fait  entrer  cent.”  * Nor 
should  we  overlook  the  effects  of  fires,  the 
demolition  of  old  buildings,  and  the  removal  of 
rubbish  to  the  nearest  vacant  space. 

Abinger,  Surrey. — Late  in  the  autumn  of 
1876,  the  ground  in  an  old  farm-yard  at  this 
place  was  dug  to  a depth  of  2 to  2J  feet,  and 
the  workmen  found  various  ancient  remains. 
This  led  Mr.  T.  H.  Farrer  of  Abinger  Hall  to 
have  an  adjoining  ploughed  field  searched. 
On  a trench  being  dug,  a layer  of  concrete, 
still  partly  covered  with  tesserae  (small  red 
tiles),  and  surrounded  on  two  sides  by  broken- 
down  walls,  was  soon  discovered.  It  is  be- 
lieved f that  this  room  formed  part  of  the 
atrium  or  reception-room  of  a Roman  villa. 
The  walls  of  two  or  three  other  small  rooms 
were  afterwards  discovered.  Many  frag- 
ments of  pottery,  other  objects,  and  coins  of 

* “ Le£ons  de  Geologie  pratique/’  1845,  p.  142. 

f A short  account  of  this  discovery  was  published  in  “ The 
Times”  of  January  2,  1878;  and  a fuller  account  in  “The 
Builder/’  January  5,  1878. 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


1 8 1 


several  Roman  emperors,  dating  from  133  to 
361,  and  perhaps  to  375  a.d.,  were  likewise 
found.  Also  a half-penny  of  George  I.,  1715. 
The  presence  of  this  latter  coin  seems  an 
anomaly;  but  no  doubt  it  was  dropped  on  the 
ground  during  the  last  century,  and  since  then 
there  has  been  ample  time  for  its  burial  under 
a considerable  depth  of  the  castings  of  worms. 
From  the  different  dates  of  the  Roman  coins 
we  may  infer  that  the  building  was  long  in- 
habited. It  was  probably  ruined  and  deserted 
1400  or  1500  years  ago. 

I was  present  during  the  commencement  of 
the  excavations  (August  20,  1877)  and  Mr. 
Farrer  had  two  deep  trenches  dug  at  opposite 
ends  of  the  atrium,  so  that  I might  examine 
the  nature  of  the  soil  near  the  remains.  The 
field  sloped  from  east  to  west  at  an  angle  of 
about  70;  and  one  of  the  two  trenches,  shown 
in  the  accompanying  section  (Fig.  8)  was  at 
the  upper  or  eastern  end.  The  diagram  is  on 
the  scale  of  of  an  inch  to  an  inch;  but  the 
trench,  which  was  between  4 and  5 feet  broad, 
and  in  parts  above  5 feet  deep,  has  necessarily 
been  reduced  out  of  all  proportion.  The  fine 


182  BURIAL  OF  THE  REMAINS  Chap.  IV. 


Fig.  8. — Section  through  the  foundations  of  a buried  Roman 
villa  at  Abinger.  A A,  vegetable  mould  ; B,  dark  earth  full 
of  stones,  13  inches  in  thickness  ; C,  black  mould  ; D,  broken 
mortar  ; E,  black  mould  ; F F,  undisturbed  sub-soil ; G,  tes-  , 
serae  ; H,  concrete  ; I,  nature  unknown  ; W,  buried  wall. 


Chap.  IV.  OF  ANCIENT  BUILDINGS.  183 

mould  over  the  floor  of  the  atrium  varied  in 
thickness  from  11  to  16  inches;  and  on  the 
side  of  the  trench  in  the  section  was  a little 
over  13  inches.  After  the  mould  had  been 
removed,  the  floor  appeared  as  a whole  mod- 
erately level;  but  it  sloped  in  parts  at  an  angle 
of  i°,  and  in  one  place  near  the  outside  at  as 
much  as  8°  30'.  The  wall  surrounding  the 
pavement  was  built  of  rough  stones,  and  was 
23  inches  in  thickness  where  the  trench  was 
dug.  Its  broken  summit  was  here  13  inches, 
but  in  another  part  15  inches,  beneath  the 
surface  of  the  field,  being  covered  by  this 
thickness  of  mould.  In  one  spot,  however, 
it  rose  to  within  6 inches  of  the  surface.  On 
two  sides  of  the  room,  where  the  junction  of 
the  concrete  floor  with  the  bounding  walls 
could  be  carefully  examined,  there  was  no 
crack  or  separation.  This  trench  afterwards 
proved  to  have  been  dug  within  an  adjoining 
room  (11  ft.  by  11  ft.  6 in.  in  size),  the  exist- 
ence of  which  was  not  even  suspected  whilst 
I was  present. 

On  the  side  of  the  trench  farthest  from  the 
buried  wall  (W),  the  mould  varied  from  9 to 


1 84  BURIAL  OF  THE  REMAINS  Chap.  IV. 

14  inches  in  thickness;  it  rested  on  a mass 
(B)  23  inches  thick  of  blackish  earth,  includ- 
ing many  large  stones.  Beneath  this  was  a 
thin  bed  of  very  black  mould  (C),  then  a layer 
of  earth  full  of  fragments  of  mortar  (D),  and 
then  another  thin  bed  (about  3 inches  thick) 
(F)  of  very  black  mould,  which  rested  on  the 
undisturbed  subsoil  (F)  of  firm,  yellowish,  ar- 
gillaceous sand.  The  23-inch  bed  (B)  was 
probably  made  ground,  as  this  would  have 
brought  up  the  floor  of  the  room  to  a level 
with  that  of  the  atrium.  The  two  thin  beds 
of  black  mould  at  the  bottom  of  the  trench 
evidently  marked  two  former  land-surfaces. 
Outside  the  walls  of  the  northern  room,  many 
bones,  ashes,  oyster-shells,  broken  pottery 
and  an  entire  pot  were  subsequently  found  at 
a depth  of  16  inches  beneath  the  surface. 

The  second  trench  was  dug  on  the  western 
or  lower  side  of  the  villa:  the  mould  was  here 
only  6\  inches  in  thickness,  and  it  rested  on  a 
mass  of  fine  earth  full  of  stones,  broken  tiles 
and  fragments  of  mortar,  34  inches  in  thick- 
ness, beneath  which  was  the  undisturbed  sand. 
Most  of  this  earth  had  probably  been  washed 


Chap.  IV.  OF  ANCIENT  BUILDINGS.  185 

down  from  the  upper  part  of  the  field,  and  the 
fragments  of  stones,  tiles,  &c.,  must  have 
come  from  the  immediately  adjoining  ruins. 

It  appears  at  first  sight  a surprising  fact  that 
this  field  of  light  sandy  soil  should  have  been 
cultivated  and  ploughed  during  many  years, 
and  that  not  a vestige  of  these  buildings 
should  have  been  discovered.  No  one  even 
suspected  that  the  remains  of  a Roman  villa 
lay  hidden  close  beneath  the  surface.  But  the 
fact  is  less  surprising  when  it  is  known  that 
the  field,  as  the  bailiff  believed,  had  never 
been  ploughed  to  a greater  depth  than  4 
inches.  It  is  certain  that  when  the  land  was 
first  ploughed,  the  pavement  and  the  sur- 
rounding broken  walls  must  have  been  cov- 
ered by  at  least  4 inches  of  soil,  for  otherwise 
the  rotten  concrete  floor  would  have  been 
scored  by  the  ploughshare,  the  tesserae  torn 
up,  and  the  tops  of  the  old  walls  knocked 
down. 

When  the  concrete  and  tesserae  were  first 
cleared  over  a space  of  14  by  9 ft.,  the  floor 
which  was  coated  with  trodden-down  earth 

exhibited  no  signs  of  having  been  penetrated 

13 


1 86  BURIAL  OF  THE  REMAINS  Chap.  IV. 

by  worms;  and  although  the  overlying  fine 
mould  closely  resembled  that  which  in  many 
places  has  certainly  been  accumulated  by 
worms,  yet  it  seemed  hardly  possible  that  this 
mould  could  have  been  brought  up  by  worms 
from  beneath  the  apparently  sound  floor.  It 
seemed  also  extremely  improbable  that  the 
thick  walls,  surrounding  the  room  and  still 
united  to  the  concrete,  had  been  undermined 
by  worms,  and  had  thus  been  caused  to  sink, 
being  afterwards  covered  up  by  their  castings. 
I therefore  at  first  concluded  that  all  the  fine 
mould  above  the  ruins  had  been  washed  down 
from  the  upper  parts  of  the  field;  but  we  shall 
soon  see  that  this  conclusion  was  certainly 
erroneous,  though  much  fine  earth  is  known  to 
be  washed  down  from  the  upper  part  of  the  field 
in  its  present  ploughed  state  during  heavy 
rains. 

Although  the  concrete  floor  did  not  at  first 
appear  to  have  been  anywhere  penetrated  by 
worms,  yet  by  the  next  morning  little  cakes  of 
the  trodden-down  earth  had  been  lifted  up  by 
worms  over  the  mouths  of  seven  burrows, 
which  passed  through  the  softer  parts  of  the 


Chap.  IV.  OF  ANCIENT  BUILDINGS.  187 

naked  concrete,  or  between  the  interstices  of 
the  tesserae.  On  the  third  morning,  twenty- 
five  burrows  were  counted;  and  by  suddenly 
lifting  up  the  little  cakes  of  earth,  four  worms 
were  seen  in  the  act  of  quickly  retreating. 
Two  castings  were  thrown  up  during  the  third 
night  on  the  floor,  and  these  were  of  large  size. 
The  season  was  not  favourable  for  the  full  ac- 
tivity of  worms,  and  the  weather  had  lately 
been  hot  and  dry,  so  that  most  of  the  worms 
now  lived  at  a considerable  depth.  In  dig- 
ging the  two  trenches  many  open  burrows  and 
some  worms  were  encountered  at  between  30 
and  40  inches  beneath  the  surface;  but  at  a 
greater  depth  they  became  rare.  One  worm, 
however,  was  cut  through  at  48^,  and  another 
at  51^  inches  beneath  the  surface.  A fresh 
humus-lined  burrow  was  also  met  with  at  a 
depth  of  57  and  another  at  65^  inches.  At 
greater  depths  than  this,  neither  burrows  nor 
worms  were  seen. 

As  I wished  to  learn  how  many  worms 
lived  beneath  the  floor  of  the  atrium — a space 
of  about  14  by  9 feet — Mr.  Farrer  was  so  kind 
as  to  make  observations  for  me,  during  the 


i88 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


next  seven  weeks,  by  which  time  the  worms 
in  the  surrounding  country  were  in  full  activ- 
ity, and  were  working  near  the  surface.  It  is 
eery  improbable  that  worms  should  have  mi- 
grated from  the  adjoining  fields  into  the  small 
space  of  the  atrium,  after  the  superficial  mould 
in  which  they  prefer  to  live,  had  been  removed. 
We  may  therefore  conclude  that  the  burrows 
and  the  castings  which  were  seen  here  during 
the  ensuing  seven  weeks  were  the  work  of  the 
former  inhabitants  of  the  space.  I will  now 
give  a few  extracts  from  Mr.  Farrer’s  notes. 

Aug.  26th,  1877;  that  isj  five  days  after 
the  floor  had  been  cleared.  On  the  previous 
night  there  had  been  some  heavy  rain,  which 
washed  the  surface  clean,  and  now  the  mouths 
of  forty  burrows  were  counted.  Parts  of  the 
concrete  were  seen  to  be  solid,  and  had  never 
been  penetrated  by  worms,  and  here  the  rain- 
water lodged. 

Sept.  5th. — Tracks  of  worms,  made  during 
the  previous  night,  could  be  seen  on  the  sur- 
face of  the  floor,  and  five  or  six  vermiform 
castings  had  been  thrown  up.  These  were  de- 
faced. 


Chap.  IV.  OF  ANCIENT  BUILDINGS.  189 

Sept.  12  th.- — During  the  last  six  days,  the 
worms  have  not  been  active,  though  many 
castings  have  been  ejected  in  the  neighbour- 
ing fields;  but  on  this  day  the  earth  was  a 
little  raised  over  the  mouths  of  the  burrows, 
or  castings  were  ejected,  at  ten  fresh  points. 
These  were  defaced.  It  should  be  understood 
that  when  a fresh  burrow  is  spoken  of,  this 
generally  means  only  that  an  old  burrow  has 
been  re-opened.  Mr.  Farrer  was  repeatedly 
struck  with  the  pertinacity  with  which  the 
worms  re-opened  their  old  burrows,  even 
when  no  earth  was  ejected  from  them.  I 
have  often  observed  the  same  fact,  and  gen- 
erally the  mouths  of  the  burrows  are  protected 
by  an  accumulation  of  pebbles,  sticks  or  leaves. 
Mr.  Farrer  likewise  observed  that  the  worms 
living  beneath  the  floor  of  the  atrium  often 
collected  coarse  grains  of  sand,  and  such  little 
stones  as  they  could  find,  round  the  mouths 
of  their  burrows. 

Sept.  13th;  soft  wet  weather.  The 
mouths  of  the  burrows  were  re-opened,  or 
castings  were  ejected,  at  31  points;  these 
were  all  defaced. 


190 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


Sept.  14th;  34  fresh  holes  or  castings  all 
defaced. 

Sept.  15th;  44  fresh  holes,  only  5 castings; 
all  defaced. 

Sept.  18th;  43  fresh  holes,  8 castings;  all 
defaced. 

The  number  of  castings  on  the  surround- 
ing fields  was  now  very  large. 

Sept.  19th;  40  holes,  8 castings;  all  de- 
faced. 

Sept.  22nd;  43  holes,  only  a few  fresh  cast- 
ings; all  defaced. 

Sept.  23rd;  44  holes,  8 castings. 

Sept.  25th;  50  holes,  no  record  of  the  num- 
ber of  castings. 

Oct.  13th;  61  holes,  no  record  of  the 
number  of  castings. 

After  an  interval  of  three  years,  Mr.  Farrer, 
at  my  request,  again  looked  at  the  concrete 
floor,  and  found  the  worms  still  at  work. 

Knowing  what  great  muscular  power 
worms  possess,  and  seeing  how  soft  the  con- 
crete was  in  many  parts,  I was  not  surprised  at 
its  having  been  penetrated  by  their  burrows; 
but  it  is  a more  surprising  fact  that  the  mor- 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


I9I 

tar  between  the  rough  stones  of  the  thick 
walls  surrounding  the  rooms,  was  found  by 
Mr.  Farrer  to  have  been  penetrated  by  worms. 
On  August  26th,  that  is,  five  days  after  the 
ruins  had  been  exposed,  he  observed  four  open 
burrows  on  the  broken  summit  of  the  eastern 
wall  (W  in  Fig.  8);  and,  on  September  15th, 
other  burrows  similarly  situated  were  seen. 
It  should  also  be  noted  that  in  the  perpendicu- 
lar side  of  the  trench  (which  was  much  deeper 
than  is  represented  in  Fig.  8)  three  recent  bur- 
rows were  seen,  which  ran  obliquely  far  down 
beneath  the  base  of  the  old  wall. 

We  thus  see  that  many  worms  lived  be- 
neath the  floor  and  the  walls  of  the  atrium  at 
the  time  when  the  excavations  were  made; 
and  that  they  afterwards  almost  daily  brought 
up  earth  to  the  surface  from  a considerable 
depth.  There  is  not  the  slightest  reason  to 
doubt  that  worms  have  acted  in  this  manner 
ever  since  the  period  when  the  concrete  was 
sufficiently  decayed  to  allow  them  to  pene- 
trate it;  and  even  before  that  period  they 
would  have  lived  beneath  the  floor,  as  soon  as 
it  became  pervious  to  rain,  so  that  the  soil  be- 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


192 

neath  was  kept  damp.  The  floor  and  the 
walls  must  therefore  have  been  continually 
undermined;  and  fine  earth  must  have  been 
heaped  on  them  during  many  centuries,  per- 
haps for  a thousand  years.  If  the  burrows  be- 
neath the  floor  and  walls,  which  it  is  probable 
were  formerly  as  numerous  as  they  now  are, 
had  not  collapsed  in  the  course  of  time  in  the 
manner  formerly  explained,  the  underlying 
earth  would  have  been  riddled  with  passages 
like  a sponge;  and  as  this  was  not  the  case, 
we  may  feel  sure  that  they  have  collapsed. 
The  inevitable  result  of  such  collapsing  during 
successive  centuries,  will  have  been  the  slow 
subsidence  of  the  floor  and  of  the  walls,  and 
their  burial  beneath  the  accumulated  worm- 
castings.  The  subsidence  of  a floor,  whilst  it 
still  remains  nearly  horizontal,  may  at  first  ap- 
pear improbable;  but  the  case  presents  no 
more  real  difficulty  than  that  of  loose  objects 
strewed  on  the  surface  of  a field,  which,  as  we 
have  seen,  become  buried  several  inches  be- 
neath the  surface  in  the  course  of  a few  years, 
though  still  forming  a horizontal  layer  parallel 
to  the  surface.  The  burial  of  the  paved  and 


Chap.  IV.  OF  ANCIENT  BUILDINGS. 


193 


level  path  on  my  lawn,  which  took  place  under 
my  own  observation,  is  an  analogous  case. 
Even  those  parts  of  the  concrete  floor  which 
the  worms  could  not  penetrate  would  almost 
certainly  have  been  undermined,  and  would 
have  sunk,  like  the  great  stones  at  Leith  Hill 
Place  and  Stonehenge,  for  the  soil  would  have 
been  damp  beneath  them.  But  the  rate  of 
sinking  of  the  different  parts  would  not  have 
been  quite  equal,  and  the  floor  was  not  quite 
level.  The  foundations  of  the  boundary  walls 
lie,  as  shown  in  the  section,  at  a very  small 
depth  beneath  the  surface;  they  would  there- 
fore have  tended  to  subside  at  nearly  the  same 
rate  as  the  floor.  But  this  would  not  have  oc- 
curred if  the  foundations  had  been  deep,  as  in 
the  case  of  some  other  Roman  ruins  presently 
to  be  described. 

Finally,  we  may  infer  that  a large  part  of 
the  fine  vegetable  mould,  which  covered  the 
floor  and  the  broken-down  walls  of  this  vifla, 
in  some  places  to  a thickness  of  16  inches,  was 
brought  up  from  below  by  worms.  From 
facts  hereafter  to  be  given  there  can  be  no 
doubt  that  some  of  the  finest  earth  thus 


194 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


brought  up  will  have  been  washed  down  the 
sloping  surface  of  the  field  during  every  heavy 
shower  of  rain.  If  this  had  not  occurred  a 
greater  amount  of  mould  would  have  accumu- 
lated over  the  ruins  than  that  now  present. 
But  beside  the  castings  of  worms  and  some 
earth  brought  up  by  insects,  and  some  accumu- 
lation of  dust,  much  fine  earth  will  have  been 
washed  over  the  ruins  from  the  upper  parts  of 
the  field,  since  it  has  been  under  cultivation; 
and  from  over  the  ruins  to  the  lower  parts  of 
the  slope;  the  present  thickness  of  the  mould 
being  the  resultant  of  these  several  agencies. 

I may  here  append  a modern  instance  of 
the  sinking  of  a pavement,  communicated  to 
me  in  1871  by  Mr.  Ramsay,  Director  of  the 
Geological  Survey  of  England.  A passage 
without  a roof,  7 feet  in  length  by  3 feet  2 
inches  in  width,  led  from  his  house  into  the 
garden,  and  was  paved  with  slabs  of  Portland 
stone.  Several  of  these  slabs  were  16  inches 
square,  others  larger,  and  some  a little  smaller. 
This  pavement  had  subsided  about  3 inches 
along  the  middle  of  the  passage,  and  2 


Chap,  IV. 


OF  ANCIENT  BUILDINGS. 


I95 


inches  on  each  side,  as  could  be  seen  by  the 
lines  of  cement  by  which  the  slabs  had  been 
originally  joined  to  the  walls.  The  pavement 
had  thus  become  slightly  concave  along  the 
middle;  but  there  was  no  subsidence  at  the 
end  close  to  the  house.  Mr.  Ramsay  could 
not  account  for  this  sinking,  until  he  observed 
that  castings  of  black  mould  were  frequently 
ejected  along  the  lines  of  junction  between 
the  slabs;  and  these  castings  were  regularly 
swept  away.  The  several  lines  of  junction, 
including  those  with  the  lateral  walls,  were  al- 
together 39  feet  2 inches  in  length.  The 
pavement  did  not  present  the  appearance  of 
ever  having  been  renewed  and  the  house  was 
believed  to  have  been  built  about  eighty-seven 
years  ago.  Considering  all  these  circum- 
stances, Mr.  Ramsay  does  not  doubt  that  the 
earth  brought  up  by  the  worms  since  the 
pavement  was  first  laid  down,  or  rather  since 
the  decay  of  the  mortar  allowed  the  worms 
to  burrow  through  it,  and  therefore  within 
a much  shorter  time  than  the  eighty-seven 
years,  has  sufficed  to  cause  the  sinking  of  the 
pavement  to  the  above  amount,  except  close 


196 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


to  the  house,  where  the  ground  beneath  would 
have  been  kept  nearly  dry. 

Beaulieu  Abbey , Hampshire . — This  abbey 
was  destroyed  by  Henry  VIII.,  and  there  now 
remains  only  a portion  of  the  southern  aisle- 
wall.  It  is  believed  that  the  king  had  most  of 
the  stones  carried  away  for  building  a castle; 
and  it  is  certain  that  they  have  been  removed. 
The  position  of  the  nave-transept  was  ascer- 
tained not  long  ago  by  the  foundations  having 
been  found;  and  the  place  is  now  marked  by 
stones  let  into  the  ground.  Where  the  abbey 
formerly  stood,  there  now  extends  a smooth 
grass-covered  surface,  which  resembles  in  all 
respects  the  rest  of  the  field.  The  guardian,  a 
very  old  man,  said  the  surface  had  never  been 
levelled  in  his  time.  In  the  year  1853,  the 
Duke  of  Buccleuch  had  three  holes  dug  in  the 
turf  within  a few  yards  of  one  another,  at  the 
western  end  of  the  nave;  and  the  old  tessel- 
lated pavement  of  the  abbey  was  thus  discov- 
ered. These  holes  were  afterwards  surround- 
ed by  brickwork,  and  protected  by  trap-doors, 
so  that  the  pavement  might  be  readily  inspect- 
ed and  preserved.  When  my  son  William  ex- 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


I97 


amined  the  place  on  January  5,  1872,  he  found 
that  the  pavement  in  the  three  holes  lay  at 
depths  of  6§,  10  and  n±  inches  beneath  the 
surrounding  turf-covered  surface.  The  old 
guardian  asserted  that  he  was  often  forced  to 
remove  worm-castings  from  the  pavement; 
and  that  he  had  done  so  about  six  months  be- 
fore. My  son  collected  all  from  one  of  the 
holes,  the  area  of  which  was  5.32  square  feet, 
and  they  weighed  7.97  ounces.  Assuming 
that  this  amount  had  accumulated  in  six 
months,  the  accumulation  during  a year  on  a 
square  yard  would  be  1.68  pounds,  which, 
though  a large  amount,  is  very  small  com- 
pared with  what,  as  we  have  seen,  is  often 
ejected  on  fields  and  commons.  When  I 
visited  the  abbey  on  June  22,  1877,  the  old 
man  said  that  he  had  cleared  out  the  holes 
about  a month  before,  but  a good  many  cast- 
ings had  since  been  ejected.  I suspect  that  he 
imagined  that  he  swept  the  pavements  oftener 
than  he  really  did,  for  the  conditions  were  in 
several  respects  very  unfavourable  for  the  ac- 
cumulation of  even  a moderate  amount  of 
castings.  The  tiles  are  rather  large,  viz., 


198 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


about  5^  inches  square,  and  the  mortar  be- 
tween them  was  in  most  places  sound,  so  that 
the  worms  were  able  to  bring  up  earth  from 
below  only  at  certain  points.  The  tiles  rested 
on  a bed  of  concrete,  and  the  castings  in  con- 
sequence consisted  in  large  part  (viz.,  in  the 
proportion  of  19  to  33)  of  particles  of  mortar, 
grains  of  sand,  little  fragments  of  rock,  bricks* 
or  tile;  and  such  substances  could  hardly  be 
agreeable,  and  certainly  not  nutritious,  to 
worms. 

My  son  dug  holes  in  several  places  within 
the  former  walls  of  the  abbey,  at  a distance  of 
several  yards  from  the  above-described  bricked 
squares.  He  did  not  find  any  tiles,  though 
these  are  known  to  occur  in  some  other  parts, 
but  he  came  in  one  spot  to  concrete  on  which 
tiles  had  once  rested.  The  fine  mould  be- 
neath the  turf  on  the  sides  of  the  several  holes, 
varied  in  thickness  from  only  2 to  2 f inches, 
and  this  rested  on  a layer  from  8|  to  above  1 1 
inches  in  thickness,  consisting  of  fragments  of 
mortar  and  stone-rubbish  with  the  interstices 
compactly  filled  up  with  black  mould.  In 
the  surrounding  field,  at  a distance  of  20  yards 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


I99 

from  the  abbey,  the  fine  vegetable  mould  was 
1 1 inches  thick. 

We  may  conclude  from  these  facts  that 
when  the  abbey  was  destroyed  and  the  stones 
removed,  a layer  of  rubbish  was  left  over  the 
whole  surface,  and  that  as  soon  as  the  worms 
were  able  to  penetrate  the  decayed  concrete 
and  the  joints  between  the  tiles,  they  slowly 
filled  up  the  interstices  in  the  overlying  rub- 
bish with  their  castings,  which  were  after- 
wards accumulated  to  a thickness  of  nearly 
three  inches  over  the  whole  surface.  If  we 
add  to  this  latter  amount  the  mould  between 
the  fragments  of  stones,  some  five  or  six 
inches  of  mould  must  have  been  brought  up 
from  beneath  the  concrete  or  tiles.  The  con- 
crete or  tiles  will  consequently  have  subsided 
to  nearly  this  amount.  The  bases  of  the 
columns  of  the  aisles  are  now  buried  beneath 
mould  and  turf.  It  is  not  probable  that  they 
can  have  been  undermined  by  worms,  for 
their  foundations  would  no  doubt  have  been 
laid  at  a considerable  depth.  If  they  have 
not  subsided,  the  stones  of  which  the  col- 
umns were  constructed  must  have  been  re- 


200 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


moved  from  beneath  the  former  level  of  the 
floor. 

Chedworth , Gloucestershire . — The  remains 
of  a large  Roman  villa  were  discovered  here 
in  1866,  on  ground  which  had  been  covered 
with  wood  from  time  immemorial.  No  sus- 
picion seems  ever  to  have  been  entertained  that 
ancient  buildings  lay  buried  here,  until  a game- 
keeper,  in  digging  for  rabbits,  encountered 
some  remains.*  But  subsequently  the  tops 
of  some  stone  walls  were  detected  in  parts  of 
the  wood,  projecting  a little  above  the  surface 
of  the  ground.  Most  of  the  coins  found  here 
belonged  to  Constans  (who  died  350  a.d.)  and 
the  Constantine  family.  My  sons  Francis  and 
Horace  visited  the  place  in  November  1877, 
for  the  sake  of  ascertaining  what  part  worms 
may  have  played  in  the  burial  of  these  exten- 
sive remains.  But  the  circumstances  were 
not  favourable  for  this  object,  as  the  ruins  are 
surrounded  on  three  sides  by  rather  steep 

* Several  accounts  of  these  ruins  have  been  published  ; the 
best  is  by  Mr.  James  Farrer  in  “ Proc.  Soc.  of  Antiquaries  of 
Scotland,”  vol.  vi.,  Part  II.,  1867,  p.  278.  Also  J.  W.  Grover, 
“Journal  of  the  British  Arch.  Assoc.,”  June,  1866.  Professor 
Buckman  has  likewise  published  a pamphlet,  “Notes  on  the 
Roman  Villa  at  Chedworth,”  2nd  edit.,  1873  : Cirencester. 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


201 


banks,  down  which  earth  is  washed  during 
rainy  weather.  Moreover  most  of  the  old 
rooms  have  been  covered  with  roofs,  for  the 
protection  of  the  elegant  tessellated  pave- 
ments. 

A few  facts  may,  however,  be  given  on 
the  thickness  of  the  soil  over  these  ruins. 
Close  outside  the  northern  rooms  there  is  a 
broken  wall,  the  summit  of  which  was  covered 
by  5 inches  of  black  mould;  and  in  a hole  dug 
on  the  outer  side  of  this  wall,  where  the 
ground  had  never  before  been  disturbed,  black 
mould,  full  of  stones,  26  inches  in  thickness, 
was  found,  resting  on  the  undisturbed  sub-soil 
of  yellow  clay.  At  a depth  of  22  inches  from 
the  surface  a pig's  jaw  and  a fragment  of  a tile 
were  found.  When  the  excavations  were  first 
made,  some  large  trees  grew  over  the  ruins; 
and  the  stump  of  one  has  been  left  directly 
over  a party-wall  near  the  bath-room,  for  the 
sake  of  showing  the  thickness  of  the  superin- 
cumbent soil,  which  was  here  38  inches.  In 
one  small  room,  which,  after  being  cleared  out, 
had  not  been  roofed  over,  my  sons  observed 
the  hole  of  a worm  passing  through  the  rotten 
14 


202 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


concrete,  and  a living  worm  was  found  within 
the  concrete.  In  another  open  room  worm- 
castings  were  seen  on  the  floor,  over  which 
some  earth  had  by  this  means  been  deposited, 
and  here  grass  now  grew. 

Brading,  Isle  of  Wight. — A fine  Roman 
villa  was  discovered  here  in  1880;  and  by  the 
end  of  October  no  less  than  18  chambers  had 
been  more  or  less  cleared.  A coin  dated  337 
a.d.  was  found.  My  son  William  visited  the 
place  before  the  excavations  were  completed; 
and  he  informs  me  that  most  of  the  floors  were 
at  first  covered  with  much  rubbish  and  fallen 
stones,  having  their  interstices  completely 
filled  up  with  mould,  abounding,  as  the  work- 
men said,  with  worms,  above  which  there  was 
mould  without  any  stones.  The  whole  mass 
was  in  most  places  from  3 to  above  4 ft.  in 
thickness.  In  one  very  large  room  the  over- 
lying  earth  was  only  2 ft.  6 in.  thick;  and  after 
this  had  been  removed,  so  many  castings  were 
thrown  up  between  the  tiles  that  the  surface 
had  to  be  almost  daily  swept.  Most  of  the 
floors  were  fairly  level.  The  tops  of  the 
broken-down  walls  were  covered  in  some 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


203 


places  by  only  4 or  5 inches  of  soil,  so  that 
they  were  occasionally  struck  by  the  plough, 
but  in  other  places  they  were  covered  by  from 
13  to  18  inches  of  soil.  It  is  not  probable  that 
these  walls  could  have  been  undermined  by 
worms  and  subsided,  as  they  rested  on  a foun- 
dation of  very  hard  red  sand,  into  which 
worms  could  hardly  burrow.  The  mortar, 
however,  between  the  stones  of  the  walls  of 
a hypocaust  was  found  by  my  son  to  have  been 
penetrated  by  many  worm-burrows.  The  re- 
mains of  this  villa  stand  on  land  which  slopes 
at  an  angle  of  about  30;  and  the  land  appears 
to  have  been  long  cultivated.  Therefore  no 
doubt  a considerable  quantity  of  fine  earth  has 
been  washed  down  from  the  upper  parts  of  the 
field,  and  has  largely  aided  in  the  burial  of 
these  remains. 

Silchester,  Hampshire. — The  ruins  of  this 
small  Roman  town  have  been  better  preserved 
than  any  other  remains  of  the  kind  in  England. 
A broken  wall,  in  most  parts  from  15  to  18 
feet  in  height,  and  about  i^  mile  in  compass, 
now  surrounds  a space  of  about  100  acres  of 
cultivated  land,  on  which  a farm-house  and  a 


204 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


church  stand.*  Formerly,  when  the  weather 
was  dry,  the  lines  of  the  buried  walls  could  be 
traced  by  the  appearance  of  the  crops;  and 
recently  very  extensive  excavations  have  been 
undertaken  by  the  Duke  of  Wellington,  under 
the  superintendence  of  the  late  Rev.  J.  G. 
Joyce,  by  which  means  many  large  buildings 
have  been  discovered.  Mr.  Joyce  made  care- 
ful coloured  sections,  and  measured  the  thick- 
ness of  each  bed  of  rubbish,  whilst  the  exca- 
vations were  in  progress;  and  he  has  had  the 
kindness  to  send  me  copies  of  several  of  them. 
When  my  sons  Francis  and  Horace  visited 
these  ruins,  he  accompanied  them,  and  added 
his  notes  to  theirs. 

Mr.  Joyce  estimates  that  the  town  was  in- 
habited by  the  Romans  for  about  three  cen- 
turies; and  no  doubt  much  matter  must  have 
accumulated  within  the  walls  during  this  long 
period.  It  appears  to  have  been  destroyed  by 
fire,  and  most  of  the  stones  used  in  the  build- 
ings have  since  been  carried  away.  These  cir- 
cumstances are  unfavourable  for  ascertaining 

* These  details  are  taken  from  the  “ Penny  Encyclopaedia,” 
article,  Hampshire. 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


205 


the  part  which  worms  have  played  in  the 
burial  of  the  ruins;  but  as  careful  sections  of 
the  rubbish  overlying  an  ancient  town  have  sel- 


Fig.  9. — Section  within  a room  in  the  Basilica  at  Silchester. 
Scale  tV* 


206 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


dom  or  never  before  been  made  in  England,  I 
will  give  copies  of  the  most  characteristic  por- 
tions of  some  of  those  made  by  Mr.  Joyce. 
They  are  of  too  great  length  to  be  here  intro- 
duced entire. 

An  east  and  west  section,  30  ft.  in  length, 
was  made  across  a room  in  the  Basilica,  now 
called  the  Hall  of  the  Merchants  (Fig.  9). 
The  hard  concrete  floor,  still  covered  here  and 
there  with  tesserae,  was  found  at  3 ft.  beneath 
the  surface  of  the  field,  which  was  here  level. 
On  the  floor  there  were  two  large  piles  of 
charred  wood,  one  alone  of  which  is  shown  in 
the  part  of  the  section  here  given.  This  pile 
was  covered  by  a thin  white  layer  of  decayed 
stucco  or  plaster,  above  which  was  a mass, 
presenting  a singularly  disturbed  appearance, 
of  broken  tiles,  mortar,  rubbish  and  fine 
gravel,  together  27  inches  in  thickness.  Mr. 
Joyce  believes  that  the  gravel  was  used  in 
making  the  mortar  or  concrete,  which  has 
since  decayed,  some  of  the  lime  probably 
having  been  dissolved.  The  disturbed  state 
of  the  rubbish  may  have  been  due  to  its 
having  been  searched  for  building  stones. 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


This  bed  was  capped  by  fine  vegetable  mould, 


*5  ju  £ 


Fig.  io. — Section  within  a hall  in  the  Basilica  at  Silchester. 
Scale  -3^. 


208 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


9 inches  in  thickness.  From  these  facts  we 
may  conclude  that  the  Hall  was  burnt  down, 
and  that  much  rubbish  fell  on  the  floor, 
through  and  from  which  the  worms  slowly 
brought  up  the  mould,  now  forming  the  sur- 
face of  the  level  field. 

A section  across  the  middle  of  another  hall 
in  the  Basilica,  32  feet  6 inches  in  length, 
called  the  (Evarium,  is  shown  in  Fig.  10.  It 
appears  that  we  have  here  evidence  of  two 
fires,  separated  by  an  interval  of  time,  during 
which  the  6 inches  of  “ mortar  and  concrete 
with  broken  tiles  ” was  accumulated.  Be- 
neath one  of  the  layers  of  charred  wood,  a 
valuable  relic,  a bronze  eagle,  was  found;  and 
this  shows  that  the  soldiers  must  have  de- 
serted the  place  in  a panic.  Owing  to  the 
death  of  Mr.  Joyce,  I have  not  been  able  to  as- 
certain beneath  which  of  the  two  layers  the 
eagle  was  found.  The  bed  of  rubble  overlying 
the  undisturbed  gravel  originally  formed,  as 
I suppose,  the  floor,  for  it  stands  on  a level 
with  that  of  a corridor,  outside  the  walls  of 
the  Hall;  but  the  corridor  is  not  shown  in 
the  section  as  here  given.  The  vegetable 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


209 


mould  was  16  inches  thick  in  the  thickest 
part;  and  the  depth  from  the  surface  of  the 
field,  clothed  with  herbage,  to  the  undisturbed 
gravel,  was  40  inches. 


Mould,  20  inches 
thick. 


Rubble  with 
broken  tiles,  4 
inches  thick. 


Black  decayed 
wood,  in  thick- 
est part  6 inches 
thick. 


Gravel. 


Fig.  11. — Section  in  a block  of  buildings  in  the  middle  of  the 
town  of  Silchester. 


The  section  shown  in  Fig.  n represents 
an  excavation  made  in  the  middle  of  the  town, 
and  is  here  introduced  because  the  bed  of 


210 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


“ rich  mould  ” attained,  according  to  Mr. 
Joyce,  the  unusual  thickness  of  20  inches. 
Gravel  lay  at  the  depth  of  48  inches  from  the 


Mould,  q inches 
thick. 


Light-coloured  earth 
with  large  pieces 
of  broken  tiles,  7 
inches. 


Dark,  . fine-grained 
rubbish  with  small 
bits  of  tiles  20 
inches. 


Concrete,  4 inches. 
Stucco,  2 inches. 


Made  bottom  with 
fragments  of  tiles, 
8 inches. 


Fine  - grained  made 
ground  with  the 
debris  of  older 
buildings. 


Fig.  12. — Section  in  the  centre  of  the  Basilica  at  Silchester. 


surface;  but  it  was  not  ascertained  whether 
this  was  in  its  natural  state,  or  had  been 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


2 1 1 


brought  here  and  had  been  rammed  down,  as 
occurs  in  some  other  places. 

The  section  shown  in  Fig.  12  was  taken 
in  the  centre  of  the  Basilica,  and  though  it 
was  5 feet  in  depth,  the  natural  sub-soil  was 
not  reached.  The  bed  marked  “ concrete  ” 
was  probably  at  one  time  a floor;  and  the  beds 
beneath  seem  to  be  the  remnants  of  more  an- 
cient buildings.  The  vegetable  mould  was 
here  only  9 inches  thick.  In  some  other  sec- 
tions, not  copied,  we  likewise  have  evidence  of 
buildings  having  been  erected  over  the  ruins 
of  older  ones.  In  one  case  there  was  a layer 
of  yellow  clay  of  very  unequal  thickness  be- 
tween two  beds  of  debris,  the  lower  one  of 
which  rested  on  a floor  with  tesserae.  The  old 
broken  walls  appear  sometimes  to  have  been 
roughly  cut  down  to  a uniform  level,  so  as  to 
serve  as  the  foundations  of  a temporary  build- 
ing; and  Mr.  Joyce  suspects  that  some  of 
these  buildings  were  wattled  sheds,  plastered 
with  clay,  which  would  account  for  the  above- 
mentioned  layer  of  clay. 

Turning  now  to  the  points  which  more 
immediately  concern  us.  Worm-castings 


212 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


were  observed  on  the  floors  of  several  of  the 
rooms,  in  one  of  which  the  tessellation  was  un- 
usually perfect.  The  tesserae  here  consisted 
of  little  cubes  of  hard  sandstone  of  about  I 
inch,  several  of  which  were  loose  or  projected 
slightly  above  the  general  level.  One  or  oc- 
casionally two  open  worm-burrows  were  found 
beneath  all  the  loose  tesserae.  Worms  have 
also  penetrated  the  old  walls  of  these  ruins. 
.A  wall,  which  had  just  been  exposed  to  view 
during  the  excavations  then  in  progress,  was 
examined:  it  was  built  of  large  flints,  and  was 
1 8 inches  in  thickness.  It  appeared  sound, 
but  when  the  soil  was  removed  from  beneath, 
the  mortar  in  the  lower  part  was  found  to  be 
so  much  decayed  that  the  flints  fell  apart  from 
their  own  weight.  Here,  in  the  middle  of  the 
wall,  at  a depth  of  29  inches  beneath  the  old 
floor  and  of  49J  inches  beneath  the  surface  of 
the  field,  a living  worm  was  found,  and  the 
mortar  was  penetrated  by  several  burrows. 

A second  wall  was  exposed  to  view  for  the 
first  time,  and  an  open  burrow  was  seen  on 
its  broken  summit.  By  separating  the  flints 
this  burrow  was  traced  far  down  in  the  interior 


Chap.  IV.  OF  ANCIENT  BUILDINGS.  213 

of  the  wall;  but  as  some  of  the  flints  cohered 
firmly,  the  whole  mass  was  disturbed  in  pull- 
ing down  the  wall,  and  the  burrow  could  not 
be  traced  to  the  bottom.  The  foundations  of 
a third  wall,  which  appeared  quite  sound,  lay 
at  a depth  of  4 feet  beneath  one  of  the  floors, 
and  of  course  at  a considerably  greater  depth 
beneath  the  level  of  the  ground.  A large 
flint  was  wrenched  out  of  the  wall  at  about  a 
foot  from  the  base,  and  this  required  much 
force,  as  the  mortar  was  sound;  but  behind 
the  flint  in  the  middle  of  the  wall,  the  mortar 
was  friable,  and  here  there  were  worm-bur- 
rows. Mr.  Joyce  and  my  sons  were  surprised 
at  the  blackness  of  the  mortar  in  this  and  in 
several  other  cases,  and  at  the  presence  of 
mould  in  the  interior  of  the  walls.  Some  may 
have  been  placed  there  by  the  old  builders  in- 
stead of  mortar;  but  we  should  remember 
that  worms  line  their  burrows  with  black  hu- 
mus. Moreover  open  spaces  would  almost 
certainly  have  been  occasionally  left  between 
the  large  irregular  flints;  and  these  spaces,  we 
may  feel  sure,  would  be  filled  up  by  the  worms 
with  their  castings,  as  soon  as  they  were  able 


North.  Horizontal  line.  South, 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


214 


to  penetrate  the  wall.  Rain- 
water, oozing  down  the  bur- 
rows would  also  carry  fine 
dark-coloured  particles  into 
every  crevice.  Mr.  Joyce  was 
at  first  very  sceptical  about 
the  amount  of  work  which  I 
attributed  to  worms;  but  he 
ends  his  notes  with  reference 
to  the  last-mentioned  wall  by 
saying,  “ This  case  caused  me 
more  surprise  and  brought 
more  conviction  to  me  than 
any  other.  I should  have  said, 
and  did  say,  that  it  wTas  quite 
impossible  such  a wall  could 
have  been  penetrated  by  earth- 
worms.” 

In  almost  all  the  rooms  the 
pavement  has  sunk  consider- 
ably, especially  towards  the 
middle;  and  this  is  shown  in 
the  three  following  sections. 
The  measurements  were  made 
by  stretching  a string  tightly 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


215 


and  horizontally  over  the  floor.  The  section, 
Fig.  13,  was  taken  from  north  to  south  across 
a room,  18  feet  4 inches  in  length,  with  a 
nearly  perfect  pavement,  next  to  the  “ Red 
Wooden  Hut.”  In  the  northern  half,  the  sub- 
sidence amounted  to  5!  inches  beneath  the 
level  of  the  floor  as  it  now  stands  close  to  the 
walls;  and  it  was  greater  in  the  northern  than 
in  the  southern  half;  but,  according  to  Mr. 
Joyce,  the  entire  pavement  has  obviously  sub- 
sided. In  several  places,  the  tesserae  appeared 
as  if  drawn  a little  away  from  the  walls;  whilst 
in  other  places  they  were  still  in  close  contact 
with  them. 

In  Fig.  14,  we  see  a section  across  the 
paved  floor  of  the  southern  corridor  or  ambu- 
latory of  a quadrangle,  in  an  excavation  made 
near  “ The  Spring.”  The  floor  is  7 feet  9 
inches  wide,  and  the  broken-down  walls  now 
project  only  § of  an  inch  above  its  level.  The 
field,  which  was  in  pasture,  here  sloped  from 
north  to  south,  at  an  angle  of  30  40'.  The  na- 
ture of  the  ground  on  each  side  of  the  corridor 
is  shown  in  the  section.  It  consisted  of  earth 
full  of  stones  and  other  debris,  capped  with 


2l6 


BURIAL  OF  THE  REMAINS 


Chap.  IV. 


* 


Nature  of  the  ground  beneath  the  tesserae  unknown.  Silchester.  Scale  3V* 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


217 


dark  vegetable  mould  which  was  thicl cer  011 
the  lower  or  southern  than  on  the  no\rt^ern 
side.  The  pavement  was  nearly  level  along 
lines  parallel  to  the  side-walls,  but  had.  sunk 
in  the  middle  as  much  as  7J  inches. 

A small  room  at  no  great  distance  ■ from 
that  represented  in  Fig.  13,  had  been  enkfr§ed 
by  the  Roman  occupier  on  the  southern 
by  an  addition  of  5 feet  4 inches  in  breC 
For  this  purpose  the  southern  wall  ofi 
house  had  been  pulled  down,  but  the  four 
tions  of  the  old  wall  had  been  left  buried 
little  depth  beneath  the  pavement  of  thei  en“ 
larged  room.  Mr.  Joyce  believes  that  yhis 
buried  wall  must  have  been  built  before  ^ie 
reign  of  Claudius  II.,  who  died  270  a.  d. 
see  in  the  accompanying  section,  Fig.  15,  tliat 
the  tessellated  pavement  has  subsided  to  a 
less  degree  over  the  buried  wall  than  ek’e” 


where;  so  that  a slight  convexity  or  prot^u" 
berance  here  stretched  in  a straight  line  acro4ss 
the  room.  This  led  to  a hole  being  dug,  an  d 
the  buried  wall  was  thus  discovered. 

We  see  in  these  three  sections,  and  in  sev 
eral  others  not  given,  that  the  old  pavement 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


have  sunk  or  sagged  considerably.  Mr.  Joyce 
formerly  attributed  this  sinking  solely  to  the 
slow  settling  of  the  ground.  That  there  has 
been  some  settling  is  highly  probable,  and  it 
may  be  seen  in  section  15  that  the  pavement 
for  a width  of  5 feet  over  the  southern  en- 
largement of  the  room,  which  must  have  been 
built  on  fresh  ground,  has  sunk  a little  more 
than  on  the  old  northern  side.  But  this  sink- 
ing may  possibly  have  had  no  connection  with 
the  enlargement  of  the  room,  for  in  Fig.  13, 
one  half  of  the  pavement  has  subsided  more 
than  the  other  half  without  any  assignable 
cause.  In  a bricked  passage  to  Mr.  Joyce’s 
own  house,  laid  down  only  about  six  years 
ago,  the  same  kind  of  sinking  has  occurred  as 
in  the  ancient  buildings.  Nevertheless  it  does 
not  appear  probable  that  the  whole  amount  of 
sinking  can  be  thus  accounted  for.  The  Ro- 
man builders  excavated  the  ground  to  an  un- 
usual depth  for  the  foundations  of  their  walls, 
which  were  thick  and  solid;  it  is  therefore 
hardly  credible  that  they  should  have  been 
careless  about  the  solidity  of  the  bed  on  which 
their  tessellated  and  often  ornamented  pave- 


220 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


ments  were  laid.  The  sinking  must,  as  it  ap- 
pears to  me,  be  attributed  in  chief  part  to  the 
pavement  having  been  undermined  by  worms, 
which  we  know  are  still  at  work.  Even  Mr. 
Joyce  at  last  admitted  that  this  could  not  have 
failed  to  have  produced  a considerable  effect. 
Thus  also  the  large  quantity  of  fine  mould 
overlying  the  pavements  can  be  accounted  for, 
the  presence  of  which  would  otherwise  be  in- 
explicable. My  sons  noticed  that  in  one  room 
in  which  the  pavement  had  sagged  very  little, 
there  was  an  unusally  small  amount  of  overly- 
ing mould. 

As  the  foundations  of  the  walls  generally 
lie  at  a considerable  depth,  they  will  either 
have  not  subsided  at  all  through  the  under- 
mining action  of  worms,  or  they  will  have  sub- 
sided much  less  than  the  floor.  This  latter 
result  would  follow  from  worms  not  often 
working  deep  down  beneath  the  foundations; 
but  more  especially  from  the  walls  not  yield- 
ing when  penetrated  by  worms,  whereas  the 
successively  formed  burrows  in  a mass  of 
earth,  equal  to  one  of  the  walls  in  depth  and 
thickness,  would  have  collapsed  many  times 


[ 

Chap.  IV.  OF  ANCIENT  BUILDINGS.  221* 

since  the  desertion  of  the  ruins,  and  would 
consequently  have  shrunk  or  subsided.  As 
the  walls  cannot  have  sunk  much  or  at  all,  the 
immediately  adjoining  pavement  from  adher- 
ing to  them  will  have  been  prevented  from 
subsiding;  and  thus  the  present  curvature  of 
the  pavement  is  intelligible. 

The  circumstance  which  has  surprised  me 
most  with  respect  to  Silchester  is  that  during 
the  many  centuries  which  have  elapsed  since 
the  old  buildings  were  deserted,  the  vegetable 
mould  has  not  accumulated  over  them  to  a 
greater  thickness  than  that  here  observed.  In 
most  places  it  is  only  about  9 inches  in  thick- 
ness, but  in  some  places  12  or  even  more 
inches.  In  Fig.  11,  it  is  given  as  20  inches, 
but  this  section  was  drawn  by  Mr.  Joyce  be- 
fore his  attention  was  particularly  called  to 
this  subject.  The  land  enclosed  within  the 
old  walls  is  described  as  sloping  slightly  to  the 
south;  but  there  are  parts  which,  according  to 
Mr.  Joyce,  are  nearly  level,  and  it  appears  that 
the  mould  is  here  generally  thicker  than  else- 
where. The  surface  slopes  in  other  parts  from 
west  to  east,  and  Mr.  Joyce  describes  one  floor 


222 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


as  covered  at  the  western  end  by  rubbish  and 
mould  to  a thickness  of  2&|  inches,  and  at  the 
eastern  end  by  a thickness  of  only  inches. 
A very  slight  slope  suffices  to  cause  recent 
castings  to  flow  downwards  during  heavy 
rain,  and  thus  much  earth  will  ultimately 
reach  the  neighbouring  rills  and  streams  and 
be  carried  away.  By  this  means,  the  absence 
of  very  thick  beds  of  mould  over  these  ancient 
ruins  may,  as  I believe,  be  explained.  More- 
over most  of  the  land  here  has  long  been 
ploughed,  and  this  would  greatly  aid  the  wash- 
ing away  of  the  finer  earth  during  rainy 
weather. 

The  nature  of  the  beds  immediately  be- 
neath the  vegetable  mould  in  some  of  the 
sections  is  rather  perplexing.  We  see,  for  in- 
stance, in  the  section  of  an  excavation  in  a 
grass  meadow  (Fig.  14),  which  sloped  from 
north  to  south  at  an  angle  of  30  40',  that  the 
mould  on  the  upper  side  is  only  six  inches  and 
on  the  lower  side  nine  inches  in  thickness. 
But  this  mould  lies  on  a mass  (25^  inches  in 
thickness  on  the  upper  side)  “ of  dark  brown 
mould,”  as  described  by  Mr.  Joyce,  “ thickly 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


223 


interspersed  with  small  pebbles  and  bits  of 
tiles,  which  present  a corroded  or  worn  ap- 
pearance. The  state  of  this  dark-coloured 
earth  is  like  that  of  a field  which  has  long  been 
ploughed,  for  the  earth  thus  becomes  inter- 
mingled with  stones  and  fragments  of  all  kinds 
which  have  been  much  exposed  to  the  weather. 

If  during  the  course  of  many  centuries  this 
grass  meadow  and  the  other  now  cultivated 
fields  have  been  at  times  ploughed,  and  at 
other  times  left  as  pasture,  the  nature  of  the 
ground  in  the  ab*ove  section  is  rendered  in- 
telligible. For  worms  will  continually  have 
brought  up  fine  earth  from  below,  which  will  > 
have  been  stirred  up  by  the  plough  whenever 
the  land  was  cultivated.  But  after  a time  a 
greater  thickness  of  fine  earth  will  thus  have 
been  accumulated  than  could  be  reached  by 
the  plough;  and  a bed  like  the  25^-inch  mass, 
in  Fig.  14,  will  have  been  formed  beneath  the 
superficial  mould,  which  latter  will  have  been 
brought  to  the  surface  within  more  recent 
times,  and  have  been  well  sifted  by  the  worms. 

Wroxeter , Shropshire. — The  old  Roman 
city  of  Uriconium  was  founded  in  the  early 


224 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


part  of  the  second  century,  if  not  before  this 
date,  and  it  was  destroyed,  according  to  Mr. 
Wright,  probably  between  the  middle  of  the 
fourth  and  fifth  century.  The  inhabitants 
were  massacred,  and  skeletons  of  women  were 
found  in  the  hypocausts.  Before  the  year 
1859,  the  sole  remnant  of  the  city  above 
ground,  was  a portion  of  a massive  wall  about 
20  ft.  in  height.  The  surrounding  land  undu- 
lates slightly,  and  has  long  been  under  cultiva- 
tion. It  had  been  noticed  that  the  corn-crops 
ripened  prematurely  in  certain  narrow  lines, 
and  that  the  snow  remained  unmelted  in  cer- 
tain places  longer  than  in  others.  These  ap- 
pearances led,  as  I was  informed,  to  extensive 
excavations  being  undertaken.  The  founda- 
tions of  many  large  buildings  and  several 
streets  have  thus  been  exposed  to  view.  The 
space  enclosed  within  the  old  walls  is  an  ir- 
regular oval,  about  if  mile  in  length.  Many 
of  the  stones  or  bricks  used  in  the  buildings 
must  have  been  carried  away;  but  the  hypo- 
causts, baths,  and  other  underground  build- 
ings were  found  tolerably  perfect,  being  filled 
with  stones,  broken  tiles,  rubbish  and  soil. 


OF  ANCIENT  BUILDINGS. 


Chap.  IV. 


225 


The  old  floors  of  various  rooms  were  covered 
with  rubble.  As  I was  anxious  to  know  how 
thick  the  mantle  of  mould  and  rubbish  was, 
which  had  so  long  concealed  these  ruins,  I ap- 
plied to  Dr.  H.  Johnson,  who  had  superintend- 
ed the  excavations;  and  he,  with  the  greatest 
kindness,  twice  visited  the  place  to  examine  it 
in  reference  to  my  questions,  and  had  many 
trenches  dug  in  four  fields  which  had  hitherto 
been  undisturbed.  The  results  of  his  obser- 
vations are  given  in  the  following  Table.  He 
also  sent  me  specimens  of  the  mould,  and  an- 
swered, as  far  as  he  could,  all  my  questions. 


Measurements  by  Dr.  H.  Johnson  of  the.  Thickness  of 
the  Vegetable  Mould  over  the  Roman  Ruins  at 
Wroxeter. 

Trenches  dug  in  a field  called  “ Old 
Works.” 

Thickness 
of  mould  in 
inches. 

1.  At  a depth  of  36  inches  undisturbed  sand  was 

reached  . . . . . . . . . . 20 

2.  At  a depth  of  33  inches  concrete  was  reached  21 

3.  “ “ 9 inches  concrete  was  reached  9 


Trenches  dug  in  a field  called  “ Shop  Lea- 
sows;.”  this  is  the  highest  field  within  the 


226 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


old  walls,  and  slopes  down  from  a sub-central 
point  on  all  sides  at  about  an  angle  of  2°. 


Thickness 
of  mould  in 
inches. 

4.  Summit  of  field,  trench  45  inches  deep  . . 40 

5.  Close  to  summit  of  field,  trench  36  inches  deep  26 

6.  “ “ trench  28  inches  deep  28 

7.  Near  summit  of  field,  trench  36  inches  deep  24 

8.  “ “ trench  at  one  end  39 

inches  deep  ; the  mould  here  graduated  into 
the  underlying  undisturbed  sand,  and  its 
thickness  is  somewhat  arbitrary.  At  the 
other  end  of  the  trench,  a causeway  was  en- 
countered at  a depth  of  only  7 inches,  and 

the  mould  was  here  only  7 inches  thick  . . 24 

9.  Trench  close  to  the  last,  28  inches  in  depth  . . 15 

10.  Lower  part  of  same  field,  trench  30  inches  deep  15 

11.  “ “ trench  31  inches  deep  17 

12.  “ “ trench  36  inches  deep, 

at  which  depth  undisturbed  sand  was  reached  28 

13.  In  another  part  of  same  field,  trench  9^  inches 


deep,  stopped  by  concrete  . . . . . . 9-J 

14.  In  another  part  of  same  field,  trench  9 inches 

deep,  stopped  by  concrete  . . . . . . 9 

15.  In  another  part  of  the  same  field,  trench  24 

inches  deep,  when  sand  was  reached  . . 16 

16.  In  another  part  of  same  field,  trench  30  inches 

deep,  when  stones  were  reached  ; at  one  end 
of  the  trench  mould  12  inches,  at  the  other 
end  14  inches  thick  . . . . . . 13 


Small  field  between  “ Old  Works  ” and 
“ Shop  Leasows,”  I believe  nearly  as  high  as 
the  upper  part  of  the  latter  field. 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


227 


Thickness 
of  mould  in 
inches. 


17.  Trench  26  inches  deep  . . . . . . 24 

18.  “ 10  inches  deep,  and  then  came  upon  a 

causeway  . . . . . . . . . . 10 

ig.  Trench  34  inches  deep  . . . . . . . . 30 

20.  “ 31  inches  deep  . . . . . . . . 31 


Field  on  the  western  side  of  the  space  en- 
closed within  the  old  walls. 

Thickness 
of  mould  in 
inches. 

21.  Trench  28  inches  deep,  when  undisturbed  sand 

was  reached  . . . . . . . . 16 

22.  Trench  29  inches  deep,  when  undisturbed  sand 

was  reached  . . . . . . . . . . 15 

23.  Trench  14  inches  deep,  and  then  came  upon  a 

building  . . . . . . . . 14 

Dr.  Johnson  distinguished  as  mould  the 
earth  which  differed,  more  or  less  abruptly,  in 
its  dark  colour  and  in  its  texture  from  the 
underlying  sand  or  rubble.  In  the  specimens 
sent  to  me,  the  mould  resembled  that  which 
lies  immediately  beneath  the  turf  in  old  pas- 
ture-land, excepting  that  it  often  contained 
small  stones,  too  large  to  have  passed  through 
the  bodies  of  worms.  But  the  trenches  above 
described  were  dug  in  fields,  none  of  which 
were  in  pasture,  and  all  had  been  long  culti- 
vated. Bearing  in  mind  the  remarks  made  in 


228 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


reference  to  Silchester  on  the  effects  of  long- 
continued  culture,  combined  with  the  action 
of  worms  in  bringing  up  the  finer  particles  to 
the  surface,  the  mould,  as  so  designated  by 
Dr.  Johnson,  seems  fairly  well  to  deserve  its 
name.  Its  thickness,  where  there  was  no 
causeway,  floor  or  walls  beneath,  was  greater 
than  has  been  elsewhere  observed,  namely  in 
many  places  above  2 ft.,  and  in  one  spot  above 
3 ft.  The  mould  was  thickest  on  and  close  to 
the  nearly  level  summit  of  the  field  called 
“ Shop  Leasows,”  and  in  a small  adjoining 
field,  which,  as  I believe,  is  of  nearly  the  same 
height.  One  side  of  the  former  field  slopes  at 
an  angle  of  rather  above  2°,  and  I should  have 
expected  that  the  mould  from  being  washed 
down  during  heavy  rain,  would  have  been 
thicker  in  the  lower  than  in  the  upper  part; 
but  this  was  not  the  case  in  two  out  of  the 
three  trenches  here  dug. 

In  many  places,  where  streets  ran  beneath 
the  surface,  or  where  old  buildings  stood,  the 
mould  was  only  8 inches  in  thickness;  and  Dr. 
Johnson  was  surprised  that  in  ploughing  the 
land,  the  ruins  had  never  been  struck  by  the 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


229 


plough  as  far  as  he  had  heard.  He  thinks  that 
when  the  land  was  first  cultivated  the  old  walls 
were  perhaps  intentionally  pulled  down,  and 
that  hollow  places  were  filled  up.  This  may 
have  been  the  case;  but  if  after  the  desertion 
of  the  city  the  land  was  left  for  many  centuries 
uncultivated,  worms  would  have  brought  up 
enough  fine  earth  to  have  covered  the  ruins 
completely;  that  is  if  they  had  subsided  from 
having  been  undermined.  The  foundations  of 
some  of  the  walls,  for  instance  those  of  the 
portion  still  standing  about  20  feet  above  the 
ground,  and  those  of  the  market-place,  lie  at 
the  extraordinary  depth  of  14  feet;  but  it  is 
highly  improbable  that  the  foundations  were 
generally  so  deep.  The  mortar  employed  in 
the  buildings  must  have  been  excellent,  for  it 
is  still  in  parts  extremely  hard.  Wherever 
walls  of  any  height  have  been  exposed  to  view, 
they  are,  as  Dr.  Johnson  believes,  still  perpen- 
dicular. The  walls  with  such  deep  founda- 
tions cannot  have  been  undermined  by  worms, 
and  therefore  cannot  have  subsided,  as  appears 
to  have  occurred  at  Abinger  and  Silchester. 
Hence  it  is  very  difficult  to  account  for  their 


230 


BURIAL  OF  THE  REMAINS  Chap.  IV. 


being  now  completely  covered  with  earth;  but 
how  much  of  this  covering  consists  of  vegeta- 
ble mould  and  how  much  of  rubble  I do  not 
know.  The  market-place,  with  the  founda- 
tions at  a depth  of  14  feet,  was  covered  up,  as 
Dr.  Johnson  believes,  by  between  6 and  24 
inches  of  earth.  The  tops  of  the  broken- 
down  walls  of  a caldarium  or  bath,  9 feet  in 
depth,  were  likewise  covered  up  with  nearly  2 
feet  of  earth.  The  summit  of  an  arch,  leading 
into  an  ash-pit  7 feet  in  depth,  was  covered  up 
with  not  more  than  8 inches  of  earth.  When- 
ever a building  which  has  not  subsided  is  cov- 
eered with  earth,  we  must  suppose,  either  that 
the  upper  layers  of  stone  have  been  at  some 
time  carried  away  by  man,  or  that  earth  has 
since  been  washed  down  during  heavy  rain,  or 
blown  down  during  storms,  from  the  adjoin- 
ing land;  and  this  would  be  especially  apt  to 
occur  where  the  land  has  long  been  cultivated. 
In  the  above  cases  the  adjoining  land  is  some- 
what higher  than  the  three  specified  sites,  as 
far  as  I can  judge  by  maps  and  from  informa- 
tion give  me  by  Dr.  Johnson.  If,  however,  a 
great  pile  of  broken  stones,  mortar,  plaster, 


Chap.  IV. 


OF  ANCIENT  BUILDINGS. 


23I 


timber,  and  ashes  fell  over  the  remains  of  any 
building,  their  disintegration  in  the  course  of 
time,  and  the  sifting  action  of  worms,  would 
ultimately  conceal  the  whole  beneath  fine 
earth. 

Conclusion. — The  cases  given  in  this  chap- 
ter show  that  worms  have  played  a consider- 
able part  in  the  burial  and  concealment  of  sev- 
eral Roman  and  other  old  buildings  in  Eng- 
land; but  no  doubt  the  washing  down  of  soil 
from  the  neighbouring  higher  lands,  and  the 
deposition  of  dust,  have  together  added  large- 
ly in  the  work  of  concealment.  Dust  would 
be  apt  to  accumulate  wherever  old  broken- 
down  walls  projected  a little  above  the  then 
existing  surface  and  thus  afforded  some  shel- 
ter. The  floors  of  the  old  rooms,  halls  and 
passages  have  generally  sunk,  partly  from  the 
settling  of  the  ground,  but  chiefly  from  having 
been  undermined  by  worms;  and  the  sinking 
has  commonly  been  greater  in  the  middle  than 
near  the  walls.  The  walls  themselves,  when- 
ever their  foundations  do  not  lie  at  a great 
depth,  have  been  penetrated  and  undermined 


232 


BURIAL  OF  THE  REMAINS.  Chap.  IV. 


by  worms,  and  have  consequently  subsided. 
The  unequal  subsidence  thus  caused,  probably 
explains  the  great  cracks  which  may  be  seen 
in  many  ancient  walls,  as  well  as  their  inclina- 
tion from  the  perpendicular. 


CHAPTER  V. 


THE  ACTION  OF  WORMS  IN  THE  DENUDATION 
OF  THE  LAND. 

Evidence  of  the  amount  of  denudation  which  the  land  has 
undergone — Subaerial  denudation — The  deposition  of  dust — 
Vegetable  mould,  its  dark  colour  and  fine  texture  largely  due 
to  the  action  of  worms — The  disintegration  of  rocks  by  the 
humus-acids — Similar  acids  apparently  generated  within  the 
bodies  of  worms — The  action  of  these  acids  facilitated  by  the 
continued  movement  of  the  particles  of  earth— A thick  bed  of 
mould  checks  the  disintegration  of  the  underlying  soil  and 
rocks. — Particles  of  stone  worn  or  triturated  in  the  gizzards  of 
worms — Swallowed  stones  serve  as  mill-stones — The  levi- 
gated state  of  the  castings — Fragments  of  brick  in  the  castings 
over  ancient  buildings  well  rounded.  The  triturating  power  of 
worms  not  quite  insignificant  under  a geological  point  of  view. 

No  one  doubts  that  our  world  at  one  time 
consisted  of  crystalline  rocks,  and  that  it  is 
to  their  disintegration  through  the  action  of 
air,  water,  changes  of  temperature,  rivers, 
waves  of  the  sea,  earthquakes  and  volcanic  out- 
bursts, that  we  owe  our  sedimentary  forma- 
tions. These  after  being  consolidated  and 

sometimes  recrystallized,  have  often  been  again 

16  233 


234 


DISINTEGRATION 


Chap.  V. 


disintegrated.  Denudation  means  the  removal 
of  such  disintegrated  matter  to  a lower  level. 
Of  the  many  striking  results  due  to  the  mod- 
ern progress  of  geology  there  are  hardly  any 
more  striking  than  those  which  relate  to 
denudation.  It  was  long  ago  seen  that  there 
must  have  been  an  immense  amount  of  denu- 
dation; but  until  the  successive  formations 
were  carefully  mapped  and  measured,  no  one 
fully  realised  how  great  was  the  amount.  One 
of  the  first  and  most  remarkable  memoirs  ever 
published  on  this  subject  was  that  by  Ram- 
say,* who  in  1846  showed  that  in  Wales  from 
9,000  to  11,000  feet  in  thickness  of  solid  rock 
had  been  stripped  off  large  tracts  of  country. 
Perhaps  the  plainest  evidence  of  great  denu- 
dation is  afforded  by  faults  or  cracks,  which  ex- 
tend for  many  miles  across  certain  districts, 
with  the  strata  on  one  side  raised  even  ten 
thousand  feet  above  the  corresponding  strata 
on  the  opposite  side;  and  yet  there  is  not  a 
vestige  of  this  gigantic  displacement  visible 
on  the  surface  of  the  land.  A huge  pile  of 

* “ On  the  denudation  of  South  Wales,”  &c.,  “ Memoirs  of 
the  Geological  Survey  of  Great  Britain,”  vol.  i.  p.  297,  1846. 


Chap.  V. 


AND  DENUDATION. 


23S 

rock  has  been  planed  away  on  one  side  and  not 
a remnant  left. 

Until  the  last  twenty  or  thirty  years,  most 
geologists  thought  that  the  waves  of  the*sea 
were  the  chief  agents  in  the  work  of  denuda- 
tion; but  we  may  now  feel  sure  that  air  and 
rain,  aided  by  streams  and  rivers,  are  much 
more  powerful  agents, — that  is  if  we  consider 
the  whole  area  of  the  land.  The  long  lines  of 
escarpment  which  stretch  across  several  parts 
of  England  were  formerly  considered  to  be  un- 
doubtedly ancient  coast-lines;  but  we  now 
know  that  they  stand  up  above  the  general 
surface  merely  from  resisting  air,  rain  and  frost 
better  than  the  adjoining  formations.  It  has 
rarely  been  the  good  fortune  of  a geologist  to 
bring  conviction  to  the  minds  of  his  fellow- 
workers  on  a disputed  point  by  a single  mem- 
oir; but  Mr.  Whitaker,  of  the  Geological 
Survey  of  England,  was  so  fortunate  when,  in 
1867,  he  published  his  paper  “ On  sub-aerial 
Denudation,  and  on  Cliffs  and  Escarpments  of 
the  Chalk.”  * Before  this  paper  appeared, 

* 44  Geological  Magazine,”  October  and  November,  1867,  vol. 
iv.  pp.  447  and  483.  Copious  references  on  the  subject  are  given 
in  this  remarkable  memoir. 


236  DISINTEGRATION  Chap.  V. 

Mr.  A.  Tylor  had  adduced  important  evidence 
on  sub-aerial  denudation,  by  showing  that  the 
amount  of  matter  brought  down  by  rivers  must 
infallibly  lower  the  level  of  their  drainage- 
basins  by  many  feet  in  no  immense  lapse  of 
time.  This  line  of  argument  has  since  been 
followed  up  in  the  most  interesting  manner  by 
Archibald  Geikie,  Croll  and  others,  in  a series 
of  valuable  memoirs.*  For  the  sake  of  those 
who  have  never  attended  to  this  subject,  a sin- 
gle instance  may  be  here  given,  namely  that  of 
the  Mississippi,  which  is  chosen  because  the 
amount  of  sediment  brought  down  by  this 
great  river  has  been  investigated  with  especial 
care  by  order  of  the  United  States  Govern- 
ment. The  result  is,  as  Mr.  Croll  shows,  that 
the  mean  level  of  its  enormous  area  of  drain- 

* A.  Tylor  “ On  changes  of  the  sea-level,”  &c.,  “Philosophical 
Mag.”  (Ser.  4th),  vol.  v.,  1853,  p.  258.  Archibald  Geikie, 
“Transactions  Geolog.  Soc.  of  Glasgow,”  vol.  iii.  p,  153  (read 
March,  1868).  Croll  “ On  Geological  Time,”  “ Philosophical 
Mag.,”  May,  August,  and  November,  1868.  See  also  Croll, 
“Climate  and  Time,”  1875,  Chap.  XX.  For  some  recent  in- 
formation on  the  amount  of  sediment  brought  down  by  rivers, 
see  “Nature,”  Sept.  23rd,  1880.  Mr.  T.  Mellard  Reade  has 
published  some  interesting  articles  on  the  astonishing  amount 
of  matter  brought  down  in  solution  by  rivers.  See  Address, 
Geolog.  Soc.,  Liverpool,  1 876-77. 


Chap.  V. 


AND  DENUDATION. 


237 


age  must  be  lowered  of  a foot  annually, 

or  1 foot  in  4566  years.  Consequently,  tak- 
ing the  best  estimate  of  the  mean  height  of 
the  North  American  continent,  viz.  748  feet, 
and  looking  to  the  future,  the  whole  of  the 
Mississippi  basin  will  be  washed  away,  and 
“ brought  down  to  the  sea-level  in  less  than 
4,500,000  years,  if  no  elevation  of  the  land 
takes  place.”  Some  rivers  carry  down  much 
more  sediment  relatively  to  their  size,  and  some 

much  less  than  the  Mississippi. 

% 

Disintegrated  matter  is  carried  away  by 
the  wind  as  well  as  by  running  water.  Dur- 
ing volcanic  outbursts  much  rock  is  triturated 
and  is  thus  widely  dispersed;  and  in  all  arid 
countries  the  wind  plays  an  important  part  in 
the  removal  of  such  matter.  Wind-driven 
sand  also  wears  down  the  hardest  rocks.  I 
have  shown  * that  during  four  months  of  the 
year  a large  quantity  of  dust  is  blown  from  the 
north-western  shores  of  Africa,  and  falls  on 
the  Atlantic  over  a space  of  1600  miles  in  lati- 
tude, and  for  a distance  of  from  300  to  600 

* “An  account  of  the  fine  dust  which  often  falls  on  vessels  in 
the  Atlantic  Ocean,”  Proc.  Geolog.  Soc.  of  London,  June  4, 1845. 


238  DISINTEGRATION  Chap.  V. 

miles  from  the  coast.  But  dust  has  been  seen 
to  fall  at  a distance  of  1030  miles  from  the 
shores  of  Africa.  During  a stay  of  three  weeks 
at  St.  Jago  in  the  Cape  Verde  Archipelago, 
the  atmosphere  was  almost  always  hazy,  and 
extremely  fine  dust  coming  from  Africa  was 
continually  falling.  In  some  of  this  dust  which 
fell  in  the  open  ocean  at  a distance  of  between 
330  and  380  miles  from  the  African  coast,  there 
were  many  particles  of  stone,  about  toVo  °f  an 
inch  square.  Nearer  to  the  coast  the  water  has 
been  seen  to  be  so  much  discoloured  by  the  fall- 
ing dust,  that  a sailing  vessel  left  a track  be- 
hind her.  In  countries,  like  the  Cape  Verde 
Archipelago,  where  it  seldom  rains  and  there 
are  no  frosts,  the  solid  rock  nevertheless  dis- 
integrates; and  in  conformity  with  the  views 
lately  advanced  by  a distinguished  Belgian 
geologist,  De  Koninck,  such  disintegration 
may  be  attributed  in  chief  part  to  the  action  of 
the  carbonic  and  nitric  acids,  together  with 
the  nitrates  and  nitrites  of  ammonia,  dissolved 
in  the  dew. 

In  all  humid,  even  moderately  humid, 
countries,  worms  aid  in  the  work  of  denuda- 


Chap.  V. 


AND  DENUDATION. 


239 


tion  in  several  ways.  The  vegetable  mould 
which  covers,  as  with  a mantle,  the  surface  of 
the  land,  has  all  passed  many  times  through 
their  bodies.  Mould  differs  in  appearance 
from  the  subsoil  only  in  its  dark  colour,  and  in 
the  absence  of  fragments  or  particles  of  stone 
(when  such  are  present  in  the  subsoil),  larger 
than  those  which  can  pass  through  the  alimen- 
tary canal  of  a worm.  This  sifting  of  the  soil 
is  aided,  as  has  already  been  remarked,  by  bur- 
rowing animals  of  many  kinds,  especially  by 
ants.  In  countries  where  the  summer  is  long 
and  dry,  the  mould  in  protected  places  must 
be  largely  increased  by  dust  blown  from  other 
and  more  exposed  places.  For  instance,  the 
quantity  of  dust  sometimes  blown  over  the 
plains  of  La  Plata,  where  there  are  no  solid 
rocks,  is  so  great,  that  during  the  “ gran  seco,” 
1827  to  1830,  the  appearance  of  the  land,  which 
is  here  unenclosed,  was  so  completely  changed 
that  the  inhabitants  could  not  recognise  the 
limits  of  their  own  estates,  and  endless  lawsuits 
arose.  Immense  quantities  of  dust  are  like- 
wise blown  about  in  Egypt  and  in  the  south  of 
France.  In  China,  as  Richthofen  maintains, 


240 


DISINTEGRATION 


Chap.  V. 


beds  appearing  like  fine  sediment,  several  hun- 
dred feet  in  thickness  and  extending  over  an 
enormous  area,  owe  their  origin  to  dust  blown 
from  the  high  lands  of  central  Asia.*  In 
humid  countries  like  Great  Britain,  as  long  as 
the  land  remains  in  its  natural  state  clothed 
with  vegetation,  the  mould  in  any  one  place 
can  hardly  be  much  increased  by  dust;  but  in 
its  present  condition,  the  fields  near  high  roads, 
where  there  is  much  traffic,  must  receive  a con- 
siderable amount  of  dust,  and  when  fields  are 
harrowed  during  dry  and  windy  weather,  clouds 
of  dust  may  be  seen  to  be  blown  away.  But 
in  all  these  cases  the  surface-soil  is  merely 
transported  from  one  place  to  another.  The 
dust  which  falls  so  thickly  within  our  houses 
consists  largely  of  organic  matter,  and  if 
spread  over  the  land  would  in  time  decay  and 

* For  La  Plata,  see  my  “Journal  of  Researches,”  during  the 
voyage  of  the  B eagle , 1845,  p.  133.  Elie  de  Beaumont  has 
given  (“  Le9ons  de  Geolog.  pratique,”  tom.  1.,  1845,  p.  183)  an 
excellent  account  of  the  enormous  quantity  of  dust  which  is 
transported  in  some  countries.  I cannot  but  think  that  Mr. 
Proctor  has  somewhat  exaggerated  (“  Pleasant  Ways  in  Science,” 
1879,  p.  379)  the  agency  of  dust  in  a humid  country  like  Great 
Britain.  James  Geikie  has  given  (“Prehistoric  Europe,”  1880, 
p.  165)  a full  abstract  of  Richthofen’s  views,  which,  however, 
he  disputes. 


Chap.  V. 


AND  DENUDATION. 


24I 


disappear  almost  entirely.  It  appears,  how- 
ever, from  recent  observations  on  the  snow- 
fields  of  the  Arctic  regions,  that  some  little 
meteoric  dust  of  extra  mundane  origin  is  con- 
tinually falling. 

The  dark  colour  of  ordinary  mould  is  ob- 
viously due  to  the  presence  of  decaying  or- 
ganic matter,  which,  however,  is  present  in  but 
small  quantities.  The  loss  of  weight  which 
mould  suffers  when  heated  to  redness  seems 
to  be  in  large  part  due  to  water  in  combina- 
tion being  dispelled.  In  one  sample  of  fertile 
mould  the  amount  of  organic  matter  was  as- 
certained to  be  only  1.76  per  cent.;  in  some 
artificially  prepared  soil  it  was  as  much  as  5.5 
per  cent.,  and  in  the  famous  black  soil  of  Russia 
from  5 to  even  12  per  cent.*  In  leaf-mould 
formed  exclusively  by  the  decay  of  leaves  the 
amount  is  much  greater,  and  in  peat  the 
carbon  alone  sometimes  amounts  to  64  per 
cent.;  but  with  these  latter  cases  we  are  not 
here  concerned.  The  carbon  in  the  soi1  tends 

* These  statements  are  taken  from  Von  Hensen  in  “Zeit- 
schrift  fur  wissenschaft.  Zoologie,”  Bd.  xxviii.,  1877,  p.  360. 
Those  with  respect  to  peat  are  taken  from  Mr.  A.  A.  Julien  in 
“ Proc.  American  Assoc.  Science,”  1879,  P*  S1^ 


242 


DISINTEGRATION 


Chap.  V. 


gradually  to  oxidise  and  to  disappear,  except 
where  water  accumulates  and  the  climate  is 
cool;  * so  that  in  the  oldest  pasture-land  there 
is  no  great  excess  of  organic  matter,  notwith- 
standing the  continued  decay  of  the  roots  and 
the  underground  stems  of  plants,  and  the  oc- 
casional addition  of  manure.  The  disappear- 
ance of  the  organic  matter  from  mould  is  prob- 
ably much  aided  by  its  being  brought  again 
and  again  to  the  surface  in  the  castings  of 
worms. 

Worms,  on  the  other  hand,  add  largely  to 
the  organic  matter  in  the  soil  by  the  astonish- 
ing number  of  half-decayed  leaves  which  they 
draw  into  their  burrows  tp  a depth  of  2 or  3 
inches.  They  do  this  chiefly  for  obtaining 
food,  but  partly  for  closing  the  mouths  of  their 
burrows  and  for  lining  the  upper  part.  The 
leaves  which  they  consume  are  moistened, 
torn  into  small  shreds,  partially  digested,  and 
intimately  commingled  with  earth;  and  it  is 
this  process  which  gives  to  vegetable  mould 
its  uniform  dark  tint.  It  is  known  that  vari- 

* I have  given  some  facts  on  the  climate  necessary  or  favour- 
able for  the  formation  of  peat,  in  my  “Journal  of  Researches/* 
1845,  p.  287. 


Chap.  V. 


AND  DENUDATION. 


243 


ous  kinds  of  acids  are  generated  by  the  decay 
of  vegetable  matter;  and  from  the  contents 
of  the  intestines  of  worms  and  from  their  cast- 
ings being  acid,  it  seems  probable  that  the  pro- 
cess of  digestion  induces  an  analogous  chemi- 
cal change  in  the  swallowed,  triturated,  and 
half-decayed  leaves.  The  large  quantity  of 
carbonate  of  lime  secreted  by  the  calciferous 
glands  apparently  serves  to  neutralise  the 
acids  thus  generated;  for  the  digestive  fluid  of 
worms  will  not  act  unless  it  be  alkaline.  As 
the  contents  of  the  upper  part  of  their  intes- 
tines are  acid,  the  acidity  can  hardly  be  due 
to  the  presence  of  uric  acid.  We  may  there- 
fore conclude  that  the  acids  in  the  alimentary 
canal  of  worms  are  formed  during  the  digest- 
ive process;  and  that  probably  they  are  nearly 
of  the  same  nature  as  those  in  ordinary  hu- 
mus. The  latter  are  well  known  to  have  the 
power  of  de-oxidising  or  dissolving  peroxide 
of  iron,  as  may  be  seen  wherever  peat  overlies 
red  sand,  or  where  a rotten  root  penetrates 
such  sand.  Now  I kept  some  worms  in  a pot 
filled  with  very  fine  reddish  sand,  consisting  of 
minute  particles  of  silex  coated  with  the  red 


244 


DISINTEGRATION 


Chap.  V. 


oxide  of  iron;  and  the  burrows,  which  the 
worms  made  through  this  sand,  were  lined  or 
coated  in  the  usual  manner  with  their  castings, 
formed  of  the  sand  mingled  with  their  intes- 
tinal secretions  and  the  refuse  of  the  digested 
leaves;  and  this  sand  had  almost  wholly  lost 
its  red  colour.  When  small  portions  of  it 
were  placed  under  the  microscope,  most  of 
the  grains  were  seen  to  be  transparent  and 
colourless,  owing  to  the  dissolution  of  the  ox- 
ide; whilst  almost  all  the  grains  taken  from 
other  parts  of  the  pot  were  coated  with  the 
oxide.  Acetic  acid  produced  hardly  any  effect 
on  this  sand;  and  even  hydrochloric,  nitric 
and  sulphuric  acids,  diluted  as  in  the  Pharma- 
copoeia, produced  less  effect  than  did  the  acids 
in  the  intestines  of  the  worms. 

Mr.  A.  A.  Julien  has  lately  collected  all 
the  extant  information  about  the  acids  gen- 
erated in  humus,  which,  according  to  some 
chemists,  amount  to  more  than  a dozen  differ- 
ent kinds.  These  acids,  as  well  as  their  acid 
salts  (i.  e.,  in  combination  with  potash,  soda, 
and  ammonia),  act  energetically  on  carbonate 
of  lime  and  on  the  oxides  of  iron.  It  is,  also, 


Chap.  V. 


AND  DENUDATION. 


245 


known  that  some  of  these  acids,  which  were 
called  long  ago  by  Thenard  azohumic,  are  en- 
abled to  dissolve  colloid  silica  in  proportion 
to  the  nitrogen  which  they  contain.*  In  the 
formation  of  these  latter  acids  worms  probably 
afford  some  aid,  for  Dr.  H.  Johnson  informs 
me  that  by  Nessler’s  test  he  found  0.018  per 
cent,  of  ammonia  in  their  castings. 

The  several  humus-acids,  which  appear,  as 
we  have  just  seen,  to  be  generated  within  the 
bodies  of  worms  during  the  digestive  process, 
and  their  acid  salts,  play  a highly  important 
part,  according  to  the  recent  observations  of 
Mr.  Julien,  in  the  disintegration  of  various 
kinds  of  rocks.  It  has  long  been  known  that 
the  carbonic  acid,  and  no  doubt  nitric  and 
nitrous  acids,  which  are  present  in  rain-water, 
act  in  like  manner.  There  is,  also,  a great  ex- 
cess of  carbonic  acid  in  all  soils,  especially  in 
rich  soils,  and  this  is  dissolved  by  the  water 
in  the  ground.  The  living  roots  of  plants, 

* A.  A.  Julien  “On  the  Geological  Action  of  the  Humus- 
acids,”  “Proc.  American  Assoc.  Science,”  vol.  xxviii.,  1879,  p. 
311.  Also  on  “Chemical  Erosion  on  Mountain  Summits;” 
“New  York  Academy  of  Sciences,”  Oct.  14,  1878,  as  quoted  in 
the  “American  Naturalist.”  See  also,  on  this  subject,  S.  W. 
Johnson-  “How  Crops  Feed,”  1870,  p.  138. 


246  DISINTEGRATION  Chap.  V. 

moreover,  as  Sachs  and  others  have  shown, 
quickly  corrode  and  leave  their  impressions  on 
polished  slabs  of  marble,  dolomite  and  phos- 
phate of  lime.  They  will  attack  even  basalt 
and  sandstone.*  But  we  are  not  here  con- 
cerned with  agencies  which  are  wholly  inde- 
pendent of  the  action  of  worms. 

The  combination  of  any  acid  with  a base 
is  much  facilitated  by  agitation,  as  fresh  sur- 
faces are  thus  continually  brought  into  con- 
tact. This  will  be  thoroughly  effected  with 
the  particles  of  stone  and  earth  in  the  intes- 
tines of  worms,  during  the  digestive  process; 
and  it  should  be  remembered  that  the  entire 
mass  of  the  mould  over  every  field,  passes,  in 
the  course  of  a few  years,  through  their  ali- 
mentary canals.  Moreover  as  the  old  burrows 
slowly  collapse,  and  as  fresh  castings  are  con- 
tinually brought  to  the  surface,  the  whole  su- 
perficial layer  of  mould  slowly  revolves  or  cir- 
culates; and  the  friction  of  the  particles  one 
with  another  will  rub  off  the  finest  films  of 
disintegrated  matter  as  soon  as  they  are 

* See  for  references  on  this  subject,  S.  W.  Johnson,  “ Ilow 
Crops  Feed,”  1870,  p.  326. 


Chap.  V. 


AND  DENUDATION. 


247 


formed.  Through  these  several  means,  mi- 
nute fragments  of  rocks  of  many  kinds  and 
mere  particles  in  the  soil  will  be  continually 
exposed  to  chemical  decomposition;  and  thus 
the  amount  of  soil  will  tend  to  increase. 

As  worms  line  their  burrows  with  their 
castings,  and  as  the  burrows  penetrate  to  a 
depth  of  5 or  6,  or  even  more  feet,  some  small 
amount  of  the  humus-acids  will  be  carried  far 
down,  and  will  there  act  on  the  underlying 
rocks  and  fragments  of  rock.  Thus  the  thick- 
ness of  the  soil,  if  none  be  removed  from  the 
surface,  will  steadily  though  slowly  tend  to  in- 
crease; but  the  accumulation  will  after  a time 
delay  the  disintegration  of  the  underlying 
rocks  and  of  the  more  deeply  seated  particles. 
For  the  humus-acids  which  are  generated 
chiefly  in  the  upper  layer  of  vegetable  mould, 
are  extremely  unstable  compounds,  and  are 
liable  to  decomposition  before  they  reach  any 
considerable  depth.*  A thick  bed  of  overly- 
ing soil  will  also  check  the  downward  exten- 
sion of  great  fluctuations  of  temperature,  and 

* This  statement  is  taken  from  Mr.  Julien,  “ Proc.  American 
Assoc.  Science,1 ” vol.  xxviii.,  1879,  P*  33°* 


248 


DISINTEGRATION 


Chap.  V. 


in  cold  countries  will  check  the  powerful  ac- 
tion of  frost.  The  free  access  of  air  will  like- 
wise be  excluded.  From  these  several  causes 
disintegration  would  be  almost  arrested,  if  the 
overlying  mould  were  to  increase  much  in 
thickness,  owing  to  none  or  little  being  re- 
moved from  the  surface.*  In  my  own  imme- 
diate neighbourhood  we  have  a curious  proof 
how  effectually  a few  feet  of  clay  checks  some 
change  which  goes  on  in  flints,  lying  freely  ex- 
posed; for  the  large  ones  which  have  lain  for 
some  time  on  the  surface  of  ploughed  fields 
cannot  be  used  for  building;  they  will  not 
cleave  properly  and  are  said  by  the  workmen 
to  be  rotten. f It  is  therefore  necessary  to 

* The  preservative  power  of  a layer  of  mould  and  turf  is  often 
shown  by  the  perfect  state  of  the  glacial  scratches  on  rocks  when 
first  uncovered.  Mr.  J.  Geikie  maintains,  in  his  last  very  inter- 
esting work  (“  Prehistoric  Europe,”  1881),  that  the  more  perfect 
scratches  are  probably  due  to  the  last  access  of  cold  and  increase 
of  ice,  during  the  long-continued,  intermittent  glacial  period. 

f Many  geologists  have  felt  much  surprise  at  the  complete 
disappearance  of  flints  over  wide  and  nearly  level  areas,  from 
which  the  chalk  has  been  removed  by  subaerial  denudation. 
But  the  surface  of  every  flint  is  coated  by  an  opaque  modified 
layer,  which  will  just  yield  to  a steel  point,  whilst  the  freshly- 
fractured,  translucent  surface  will  not  thus  yield.  The  removal 
by  atmospheric  agencies  of  the  outer  modified  surfaces  of  freely 
exposed  flints,  though  no  doubt  excessively  slow,  together  with 


Chap.  V. 


AND  DENUDATION. 


249 


obtain  flints  for  building  purposes  from  the 
bed  of  red  clay  overlying  the  chalk  (the  residue 
of  its  dissolution  by  rainwater)  or  from  the 
chalk  itself. 

Not  only  do  worms  aid  indirectly  in  the 
chemical  disintegration  of  rocks,  but  there  is 
good  reason  to  believe  that  they  likewise  act 
in  a direct  and  mechanical  manner  on  the 
smaller  particles.  All  the  species  which  swal- 
low earth  are  furnished  with  gizzards;  and 
these  are  lined  with  so  thick  a chitinous  mem- 
brane, that  Perrier  speaks  of  it  * as  “ une  veri- 
table armature.”  The  gizzard  is  surrounded 
by  powerful  transverse  muscles,  which,  ac- 
cording to  Claparede,  are  about  ten  times  as 
thick  as  the  longitudinal  ones;  and  Perrier  saw 
them  contracting  energetically.  Worms  be- 
longing to  one  genus,  Digaster,  have  two  dis- 
tinct but  quite  similar  gizzards;  and  in  an- 
other genus,  Moniligaster,  the  second  gizzard 
consists  of  four  pouches,  one  succeeding  the 
other,  so  that  it  may  almost  be  said  to  have 

the  modification  travelling  inwards,  will,  as  may  be  suspected, 
ultimately  lead  to  their  complete  disintegration,  notwithstanding 
that  they  appear  to  be  so  extremely  durable. 

* “Archives  de  Zoolog.  exper.,”  tom.  iii.  1874,  p.  409. 


250 


DISINTEGRATION 


Chap.  V. 


five  gizzards.*  In  the  same  manner  as  galli- 
naceous and  struthious  birds  swallow  stones  to 
aid  in  the  trituration  of  their  food,  so  it  ap- 
pears to  be  with  terricolous  worms.  The  giz- 
zards of  thirty-eight  of  our  common  worms 
were  opened,  and  in  twenty-five  of  them  small 
stones  or  grains  of  sand,  sometimes  together 
with  the  hard  calcareous  concretions  formed 
within  the  anterior  calciferous  glands,  were 
found,  and  in  two  others  concretions  alone. 
In  the  gizzards  of  the  remaining  worms  there 
were  no  stones;  but  some  of  these  were  not 
real  exceptions,  as  the  gizzards  were  opened 
late  in  the  autumn  when  the  worms  had 
ceased  to  feed  and  their  gizzards  were  quite 
empty. f 

When  worms  make  their  burrows  through 
earth  abounding  with  little  stones,  no  doubt 
many  will  be  unavoidably  swallowed;  but  it 
must  not  be  supposed  that  this  fact  accounts 
for  the  frequency  with  which  stones  and  sand 

* “ Nouvelles  Archives  du  Museum/'  tom.  viii.  1872,  pp.  95, 
131. 

f Morren,  in  speaking  of  the  earth  in  the  alimentary  canals 
of  worms,  says,  “ praesep&  cum  lapillis  commixtam  vidi ; ” “ De 
Lumbrici  terrestris,”  &c.,  1829,  p.  16. 


Chap.  V.  AND  DENUDATION.  251 

are  found  in  their  gizzards.  For  beads  of 
glass  and  fragments  of  brick  and  of  hard  tiles 
were  scattered  over  the  surface  of  the  earth, 
in  pots  in  which  worms  were  kept  and  had  al- 
ready made  their  burrows;  and  very  many  of 
these  beads  and  fragments  were  picked  up  and 
swallowed  by  the  worms,  for  they  were  found 
in  their  castings,  intestines,  and  gizzards.  They 
even  swallowed  the  coarse  red  dust,  formed 
by  the  pounding  of  the  tiles.  Nor  can  it  be 
supposed  that  they  mistook  the  beads  and 
fragments  for  food;  for  we  have  seen  that 
their  taste  is  delicate  enough  to  distinguish 
between  different  kinds  of  leaves.  It  is  there- 
fore manifest  that  they  swallow  hard  objects,  j 
such  as  bits  of  stone,  beads  of  glass  and  angu- 
lar fragments  of  bricks  or  tiles  for  some  special 
purpose;  and  it  can  hardly  be  doubted  that 
this  is  to  aid  their  gizzards  in  crushing  and 
grinding  the  earth,  which  they  so  largely  con- 
sume. That  such  hard  objects  are  not  neces- 
sary for  crushing  leaves,  may  be  inferred  from 
the  fact  that  certain  species,  which  live  in  mud 
or  water  and  feed  on  dead  or  living  vegetable 
matter,  but  which  do  not  swallow  earth,  are 


252  DISINTEGRATION  Chap.  V. 

not  provided  with  gizzards,*  and  therefore 
cannot  have  the  power  of  utilising  stones. 

During  the  grinding  process,  the  particles 
of  earth  must  be  rubbed  against  one  another, 
and  between  the  stones  and  the  tough  lining 
membrane  of  the  gizzard.  The  softer  parti- 
cles will  thus  suffer  some  attrition,  and  will 
perhaps  even  be  crushed.  This  conclusion  is 
supported  by  the  appearance  of  freshly  ejected 
castings,  for  these  often  reminded  me  of  the 
appearance  of  paint  which  has  just  been 
ground  by  a workman  between  two  flat  stones. 
Morren  remarks  that  the  intestinal  canal  is 
“ impleta  tenuissima  terra,  veluti  in  pulverem 
redacta.”  f Perrier  also  speaks  of  “ l’etat  de 
pate  excessivement  fine  a laquelle  est  reduite 
la  terre  qu’ils  rejettent,”  &c.  X 

As  the  amount  of  trituration  which  the 
particles  of  earth  undergo  in  the  gizzards  of 
worms  possesses  some  interest  (as  we  shall 
hereafter  see),  I endeavoured  to  obtain  evi- 
dence on  this  head  by  carefully  examining 

* Perrier,  “ Archives  de  Zoolog.  exper.,”  tom.  iii.  1874, 
p.  419. 

f Morren,  u De  Lumbrici  terrestris,”  &c.,  p.  16. 

X “ Archives  de  Zoolog.  exper.,”  tom.  iii.  1874,  P*  418. 


Chap.  V. 


AND  DENUDATION. 


253 


many  of  the  fragments  which  had  passed 
through  their  alimentary  canals.  With  worms 
living  in  a state  of  nature,  it  is  of  course  impos- 
sible to  know  how  much  the  fragments  may 
have  been  worn  before  they  were  swallowed. 
It  is,  however,  clear  that  worms  do  not  habitu- 
ally select  already  rounded  particles,  for  sharply 
angular  bits  of  flint  and  of  other  hard  rocks 
were  often  found  in  their  gizzards  or  intestines. 
On  three  occasions  sharp  spines  from  the  stems 
of  rose-bushes  were  thus  found.  Worms  kept 
in  confinement  repeatedly  swallowed  angular 
fragments  of  hard  tile,  coal,  cinders,  and  even 
the  sharpest  fragments  of  glass.  Gallinaceous 
and  struthious  birds  retain  the  same  stones  in 
their  gizzards  for  a long  time,  which  thus  be- 
come well  rounded;  but  this  does  not  appear 
to  be  the  case  with  worms,  judging  from  the 
large  number  of  the  fragments  of  tiles,  glass 
beads,  stones,  &c.,  commonly  found  in  their 
castings  and  intestines.  So  that  unless  the 
same  fragments  were  to  pass  repeatedly 
through  their  gizzards,  visible  signs  of  attri- 
tion in  the  fragments  could  hardly  be  expected, 
except  perhaps  in  the  case  of  very  soft  stones. 


254  DISINTEGRATION  Chap.  V. 

I will  now  give  such  evidence  of  attrition 
as  I have  been  able  to  collect.  In  the  gizzards 
of  some  worms  dug  out  of  a thin  bed  of  mould 
over  the  chalk,  there  were  many  well-rounded 
small  fragments  of  chalk,  and  two  fragments 
of  the  shells  of  a land  mollusc  (as  ascertained 
by  their  microscopical  structure),  which  latter 
were  not  only  rounded  but  somewhat  polished. 
The  calcareous  concretions  formed  in  the  cal- 
ciferous  glands,  which  are  often  found  in  their 
gizzards,  intestines,  and  occasionally  in  their 
castings,  when  of  large  size,  sometimes  ap- 
peared to  have  been  rounded;  but  with  all  cal- 
careous bodies  the  rounded  appearance  may  be 
partly  or  wholly  due  to  their  corrosion  by  car- 
bonic acid  and  the  humus-acids.  In  the  giz- 
zards of  several  worms  collected  in  my  kitchen 
garden  near  a hothouse,  eight  little  fragments 
of  cinders  were  found,  and  of  these,  six  ap- 
peared more  or  less  rounded,  as  were  two  bits 
of  brick;  and  some  other  bits  were  not  at  all 
rounded.  A farm-road  near  Abinger  Hall 
had  been  covered  seven  years  before  with 
brick-rubbish  to  the  depth  of  about  6 inches; 
turf  had  grown  over  this  rubbish  on  both  sides 


Chap.  V. 


AND  DENUDATION. 


255 


of  the  road  for  a width  of  18  inches,  and  on 
this  turf  there  were  innumerable  castings. 
Some  of  them  were  coloured  of  a uniform  red 
owing  to  the  presence  of  much  brick-dust,  and 
they  contained  many  particles  of  brick  and  of 
hard  mortar  from  1 to  3 mm.  in  diameter,  most 
of  which  were  plainly  rounded;  but  all  these 
particles  may  have  been  rounded  before  they 
were  protected  by  the  turf  and  were  swallowed, 
like  those  on  the  bare  parts  of  the  road  which 
were  much  worn.  A hole  in  a pasture-field 
had  been  filled  up  with  brick-rubbish  at  the 
same  time,  viz.,  seven  years  ago,  and  was  now 
covered  with  turf;  and  here  the  castings  con- 
tained very  many  particles  of  brick,  all  more  or 
less  rounded;  and  this  brick-rubbish,  after  be- 
ing shot  into  the  hole,  could  not  have  under- 
gone any  attrition.  Again,  old  bricks  very 
little  broken,  together  with  fragments  of  mor- 
tar, were  laid  down  to  form  walks,  and  were 
then  covered  with  from  4 to  6 inches  of  gravel; 
six  little  fragments  of  brick  were  extracted 
from  castings  collected  on  these  walks,  three 
of  which  were  plainly  worn.  There  were  also 
very  many  particles  of  hard  mortar,  about  half 


256  DISINTEGRATION  Chap.  V. 

of  which  were  well  rounded;  and  it  is  not  cred- 
ible that  these  could  have  suffered  so  much 
corrosion  from  the  action  of  carbonic  acid  in 
the  course  of  only  seven  years. 

Much  better  evidence  of  the  attrition  of 
hard  objects  in  the  gizzards  of  worms,  is  af- 
forded by  the  state  of  the  small  fragments  of 
tiles  or  bricks,  and  of  concrete  in  the  castings 
thrown  up  where  ancient  buildings  once  stood. 
As  all  the  mould  covering  a field  passes  every 
few  years  through  the  bodies  of  worms,  the 
same  small  fragments  will  probably  be  swal- 
lowed and  brought  to  the  surface  many  times 
in  the  course  of  centuries.  It  should  be  prem- 
ised that  in  the  several  following  cases,  the 
final  matter  was  first  washed  away  from  the 
castings,  and  then  all  the  particles  of  bricks, 
tiles  and  concrete  were  collected  without  any 
selection,  and  were  afterwards  examined. 
Now  in  the  castings  ejected  between  the  tes- 
serae on  one  of  the  buried  floors  of  the  Roman 
villa  at  Abinger,  there  were  many  particles 
(from  | to  2 mm.  in  diameter)  of  tiles  and 
concrete,  which  it  was  impossible  to  look  at 
with  the  naked  eye  or  through  a strong  lens, 


Chap.  V. 


AND  DENUDATION. 


257 


and  doubt  for  a moment  that  they  had  almost 
all  undergone  much  attrition.  I speak  thus 
after  having  examined  small  water-worn  peb- 
bles, formed  from  Roman  bricks,  which  M. 
Henri  de  Saussure  had  the  kindness  to  send 
me,  and  which  he  had  extracted  from  sand  and 
gravel  beds,  deposited  on  the  shores  of  the 
Lake  of  Geneva,  at  a former  period  when  the 
water  stood  at  about  two  metres  above  its 
present  level.  The  smallest  of  these  water- 
worn  pebbles  of  brick  from  Geneva  resembled 
closely  many  of  those  extracted  from  the  giz- 
zards of  worms,  but  the  larger  ones  were  some- 
what smoother. 

Four  castings  found  on  the  recently  un- 
covered, tessellated  floor  of  the  great  room  in 
the  Roman  villa  at  Brading,  contained  many 
particles  of  tile  or  brick,  of  mortar,  and  of 
hard  white  cement;  and  the  majority  of  these 
appeared  plainly  worn.  The  particles  of  mor- 
tar, however,  seemed  to  have  suffered  more 
corrosion  than  attrition,  for  grains  of  silex 
often  projected  from  their  surfaces.  Castings 
from  within  the  nave  of  Beaulieu  Abbey,  which 
was  destroyed  by  Henry  VIII.,  were  collected 


258 


DISINTEGRATION 


Chap.  V. 


from  a level  expanse  of  turf,  overlying  the 
buried  tessellated  pavement,  through  which 
worm-burrows  passed;  and  these  castings  con- 
tained innumerable  particles  of  tiles  and  bricks, 
of  concrete  and  cement,  the  majority  of  which 
had  manifestly  undergone  some  or  much  attri- 
tion. There  were  also  many  minute  flakes  of 
a micaceous  slate,  the  points  of  which  were 
rounded.  If  the  above  supposition,  that  in  all 
these  cases  the  same  minute  fragments  have 
passed  several  times  through  the  gizzards  of 
worms,  be  rejected,  notwithstanding  its  in- 
herent probability,  we  must  then  assume  that 
in  all  the  above  cases  the  many  rounded 
fragments  found  in  the  castings  had  all  ac- 
cidentally undergone  much  attrition  before 
they  were  swallowed;  and  this  is  highly  im- 
probable. 

On  the  other  hand  it  must  be  stated  that 
fragments  of  ornamental  tiles,  somewhat 
harder  than  common  tiles  or  bricks,  which  had 
been  swallowed  only  once  by  worms  kept  in 
confinement,  were  with  the  doubtful  exception 
of  one  or  two  of  the  smallest  grains,  not  at  all 
rounded.  Nevertheless  some  of  them  ap- 


Chap.  V. 


AND  DENUDATION. 


259 


peared  a little  worn,  though  not  rounded. 
Notwithstanding  these  cases,  if  we  consider 
the  evidence  above  given,  there  can  be  little 
doubt  that  the  fragments,  which  serve  as  mill- 
stones in  the  gizzards  of  worms,  suffer,  when 
of  a not  very  hard  texture,  some  amount  of 
attrition;  and  that  the  smaller  particles  in  the 
earth,  which  is  habitually  swallowed  in  such 
astonishingly  large  quantities  by  worms,  are 
ground  together  and  are  thus  levigated.  If 
this  be  the  case,  the  “ terra  tenuissima,” — the 
“ pate  excessivement  fine,” — of  which  the  cast- 
ings largely  consist,  is  in  part  due  to  the  me- 
chanical action  of  the  gizzard;  * and  this  fine 
matter,  as  we  shall  see  in  the  next  chapter, 
is  that  which  is  chiefly  washed  away  from 
the  innumerable  castings  on  every  field  dur- 
ing each  heavy  shower  of  rain.  If  the 
softer  stones  yield  at  all,  the  harder  ones 

* This  conclusion  reminds  me  of  the  vast  amount  of  extremely 
fine  chalky  mud  which  is  found  within  the  lagoons  of  many 
atolls,  where  the  sea  is  tranquil  and  waves  cannot  triturate  the 
blocks  of  coral.  This  mud  must,  as  I believe  (“  The  Structure 
and  Distribution  of  Coral-Reefs,”  2nd  edit.  1874,  p.  19),  be  at- 
tributed to  the  innumerable  annelids  and  other  animals  which 
burrow  into  the  dead  coral,  and  to  the  fishes,  Holothurians,  &c., 
which  browse  on  the  living  corals. 


26o 


DISINTEGRATION 


Chap.  V. 


will  suffer  some  slight  amount  of  wear  and 
tear. 

The  trituration  of  small  particles  of  stone 
in  the  gizzards  of  worms  is  of  more  importance 
under  a geological  point  of  view  than  may  at 
first  appear  to  be  the  case;  for  Mr.  Sorby  has 
clearly  shown  that  the  ordinary  means  of  dis- 
integration, namely  running  water  and  the 
waves  of  the  sea,  act  with  less  and  less  power 
on  fragments  of  rock  the  smaller  they  are. 
“ Hence,”  as  he  remarks,  “ even  making  no  al- 
lowance for  the  extra  buoying  up  of  very 
minute  particles  by  a current  of  water,  depend- 
ing on  surface  cohesion,  the  effects  of  wearing 
on  the  form  of  the  grains  must  vary  directly 
as  their  diameter  or  thereabouts.  If  so,  a 
grain  of  an  inch  in  diameter  would  be  worn 
ten  times  as  much  as  one  -ygy  of  an  inch  in 
diameter,  and  at  least  a hundred  times  as  much 
as  one  y-gVg  of  an  inch  in  diameter.  Perhaps, 
then,  we  may  conclude  that  a grain  yg-  of  an 
inch  in  diameter  would  be  worn  as  much  or 
more  in  drifting  a mile  as  a grain  Ttnru  of  an 
inch  in  being  drifted  ioo  miles.  On  the  same 
principle  a pebble  one  inch  in  diameter  would 


Chap.  V. 


AND  DENUDATION. 


26l 


be  worn  relatively  more  by  being  drifted  only 
a few  hundred  yards.”  * Nor  should  we  for- 
get, in  considering  the  power  which  worms 
exert  in  triturating  particles  of  rock,  that  there 
is  good  evidence  that  on  each  acre  of  land, 
which  is  sufficiently  damp  and  not  too  sandy, 
gravelly  or  rocky  for  worms  to  inhabit,  a 
weight  of  more  than  ten  tons  of  earth  annu- 
ally passes  through  their  bodies  and  is  brought 
to  the  surface.  The  result  for  a country  of  the 
size  of  Great  Britain,  within  a period  not  very 
long  in  a geological  sense,  such  as  a million 
years,  cannot  be  insignificant;  for  the  ten  tons 
of  earth  has  to  be  multiplied  first  by  the  above 
number  of  years,  and  then  by  the  number  of 
acres  fully  stocked  with  worms;  and  in  Eng- 
land, together  with  Scotland,  the  land  which 
is  cultivated  and  is  well  fitted  for  these  animals, 
has  been  estimated  at  above  32  million  acres. 
The  product  is  320  million  million  tons  of 
earth. 

* Anniversary  Address:  “The  Quarterly  Journal  of  the 
Geological  Soc.,”  May,  1880,  p.  59. 


CHAPTER  VI. 


THE  DENUDATION  OF  THE  LAND Continued. 

Denudation  aided  by  recently  ejected  castings  flowing  down 
inclined  grass-covered  surfaces — The  amount  of  earth  which 
annually  flows  downwards — The  effect  of  tropical  rain  on 
worm  castings — The  finest  particles  of  earth  washed  com- 
pletely away  from  castings — The  disintegration  of  dried  cast- 
ings into  pellets,  and  their  rolling  down  inclined  surfaces — 
The  formation  of  little  ledges  on  hill-sides,  in  part  due  to  the 
accumulation  of  disintegrated  castings — Castings  blowp  to 
leeward  over  level  land — An  attempt  to  estimate  the  amount 
thus  blown — The  degradation  of  ancient  encampments  and 
tumuli — The  preservation  of  the  crowns  and  furrows  on  land 
anciently  ploughed — The  formation  and  amount  of  mould 
over  the  Chalk  formation. 


We  are  now  prepared  to  consider  the  more 
direct  part  which  worms  take  in  the  denuda- 
tion of  the  land.  When  reflecting  on  subaerial 
denudation,  it  formerly  appeared  to  me,  as  it 
has  to  others,  that  a nearly  level  or  very  gently 
inclined  surface,  covered  with  turf,  could  suffer 
no  loss  during  even  a long  lapse  of  time.  It 
may,  however,  be  urged  that  at  long  intervals, 

debacles  of  rain  or  water-spouts  would  remove 

262 


Chap.  VI. 


AIDED  BY  WORMS. 


263 


all  the  mould  from  a very  gentle  slope;  but 
when  examining  the  steep,  turf-covered  slopes 
in  Glen  Roy,  I was  struck  with  the  fact  how 
rarely  any  such  event  could  have  happened 
since  the  Glacial  period,  as  was  plain  from  the 
well-preserved  state  of  the  three  successive 
“ roads  ” or  lake-margins.  But  the  difficulty 
in  believing  that  earth  in  any  appreciable  quan- 
tity can  be  removed  from  a gently  inclined  sur- 
face, covered  with  vegetation  and  matted  with 
roots,  is  removed  through  the  agency  of 
worms.  For  the  many  castings  which  are 
thrown  up  during  rain,  and  those  thrown  up 
some  little  time  before  heavy  rain,  flow  for  a 
short  distance  down  an  inclined  surface. 
Moreover  much  of  the  finest  levigated  earth 
is  washed  completely  away  from  the  castings. 
During  dry  weather  castings  often  disintegrate 
into  small  rounded  pellets,  and  these  from  their 
weight  often  roll  down  any  slope.  This  is 
more  especially  apt  to  occur  when  they  are 
started  by  the  wind,  and  probably  when  started 
by  the  touch  of  an  animal,  however  small. 
We  shall  also  see  that  a strong  wind  blows  all 
the  castings,  even  on  a level  field,  to  leeward, 


264 


DENUDATION  OF  THE  LAND  Chap.  VI. 


whilst  they  are  soft;  and  in  like  manner  the 
pellets  when  they  are  dry.  If  the  wind  blows 
in  nearly  the  direction  of  an  inclined  surface, 
the  flowing  down  of  the  castings  is  much  aided. 

The  observations  on  which  these  several 
statements  are  founded  must  now  be  given  in 
some  detail.  Castings  when  first  ejected  are 
^viscid  and  soft;  during  rain,  at  which  time 
worms  apparently  prefer  to  eject  them,  they  , 
are  still  softer;  so  that  I have  sometimes 
thought  that  worms  must  swallow  much  water 
at  such  times.  .However  this  may  be,  rain, 
even  when  not  very  heavy,  if  long  continued, 
renders  recently-ejected  castings  semi-fluid; 
and  on  level  ground  they  then  spread  out  into 
thin,  circular,  flat  discs,  exactly  as  would  so 
much  honey  or  very  soft  mortar,  with  all  traces 
of  their  vermiform  structure  lost.  This  latter 
fact  was  sometimes  made  evident,  when  a 
worm  had  subsequently  bored  through  a flat 
circular  disc  of  this  kind,  and  heaped  up  a 
fresh  vermiform  mass  in  the  centre.  These 
flat  subsided  discs  have  been  repeatedly  seen 
by  me  after  heavy  rain,  in  many  places  on  land 
of  all  kinds. 


Chap.  VI. 


AIDED  BY  WORMS. 


265 


On  the  flowing  of  wet  castings , and  the  roll- 
ing of  dry  disintegrated  castings  down  inclined 
surfaces . — When  castings  are  ejected  on  an  in- 
clined surface  during  or  shortly  before  heavy 
rain,  they  cannot  fail  to  flow  a little  down  the 
slope.  Thus,  on  some  steep  slopes  in  Knowle 
Park,  which  were  covered  with  coarse  grass 
and  had  apparently  existed  in  this  state  from 
time  immemorial,  I found  (Oct.  22,  1872)  after 
several  wet  days  that  almost  all  the  many  cast- 
ings were  considerably  elongated  in  the  line 
of  the  slope;  and  that  they  now  consisted  of 
smooth,  only  slightly  conical  masses.  When- 
ever the  mouths  of  the  burrows  could  be  found 
from  which  the  earth  had  been  ejected,  there 
was  more  earth  below  than  above  them.  After 
some  heavy  storms  of  rain  (Jan.  25,  1872)  two 
rather  steeply  inclined  fields  near  Down,  which 
had  formerly  been  ploughed  and  were  now 
rather  sparsely  clothed  with  poor  grass,  were 
visited,  and  many  castings  extended  down  the 
slopes  for  a length  of  5 inches,  which  was  twice 
or  thrice  the  usual  diameter  of  the  castings 
thrown  up  on  the  level  parts  of  these  same 

fields.  On  some  fine  grassy  slopes  in  Hol- 

18 


266 


DENUDATION  OF  THE  LAND  Chap.  VI. 


wood  Park,  inclined  at  angles  between  8°  and 
n°  30'  with  the  horizon,  where  the  surface  ap- 
parently had  never  been  disturbed  by  the  hand 
of  man,  castings  abounded  in  extraordinary 
numbers;  and  a space  16  inches  in  length  trans- 
versely to  the  slope  and  6 inches  in  the  line  of 
the  slope,  was  completely  coated,  between  the 
blades  of  grass,  with  a uniform  sheet  of  con- 
fluent and  subsided  castings.  Here  also  in 
many  places  the  castings  had  flowed  down  the 
slope,  and  now  formed  smooth  narrow  patches 
of  earth,  6,  7,  and  inches  in  length.  Some 
of  these  consisted  of  two  castings,  one  above 
the  other,  which  had  become  so  completely 
confluent  that  they  could  hardly  be  distin- 
guished. On  my  lawn,  clothed  with  very  fine 
grass,  most  of  the  castings  are  black,  but  some 
are  yellowish  from  earth  having  been  brought 
up  from  a greater  depth  than  usual,  and  the 
flowing-down  of  these  yellow  castings  after 
heavy  rain,  could  be  clearly  seen  where  the 
slope  was  50;  and  where  it  was  less  than  i° 
some  evidence  of  their  flowing-down  could 
still  be  detected.  On  another  occasion,  after 
rain  which  was  never  heavy,  but  which  lasted 


Chap.  VI. 


AIDED  BY  WORMS. 


267 


for  18  hours,  all  the  castings  on  this  same 
gently  inclined  lawn  had  lost  their  vermifoi 


structure;  and  they  had  flowed,  so  that  fully 
two-thirds  of  the  ejected  earth  lay  below  the 
mouths  of  the  burrows. 

These  observations  led  me  to  make  others 
with  more  care.  Eight  castings  were  found 
on  my  lawn,  where  the  grass-blades  are  fine 
and  close  together,  and  three  others  on  a field 
with  coarse  grass.  The  inclination  of  the  sur- 
face at  the  eleven  places  where  these  castings 
were  collected  varied  between  40  30'  and  170 
30';  the  mean  of  the  eleven  inclinations  being 
90  26'.  The  length  of  the  castings  in  the  di- 
rection of  the  slope  was  first  measured  with  as 
much  accuracy  as  their  irregularities  would 
permit.  It  was  found  possible  to  make  these 
measurements  within  about  -J  of  an  inch,  but 
one  of  the  castings  was  too  irregular  to  admit 
of  measurement.  The  average  length  in  the 
direction  of  the  slope  of  the  remaining  ten 
castings  was  2.03  inches.  The  castings  were 
then  divided  with  a knife  into  two  parts  along 
a horizontal  line  passing  through  the  mouth 
of  the  burrow,  which  was  discovered  by  slicing 


268 


DENUDATION  OF  THE  LAND  Chap.  VI. 


off  the  turf;  and  all  the  ejected  earth  was  sepa- 
rately collected,  namely  the  part  above  the  hole 
and  the  part  below.  Afterwards  these  two 
parts  were  weighed.  In  every  case  there  was 
much  more  earth  below  than  above;  the  mean 
weight  of  that  above  being  103  grains,  and  of 
that  below  205  grains;  so  that  the  latter  was 
very  nearly  double  the  former.  As  on  level 
ground  castings  are  commonly  thrown  up  al- 
most equally  round  the  mouths  of  the  burrows, 
this  difference  in  weight  indicates  the  amount 
of  ejected  earth  which  had  flowed  down  the 
slope.  But  very  many  more  observations 
would  be  requisite  to  arrive  at  any  general 
result;  for  the  nature  of  the  vegetation  and 
other  accidental  circumstances,  such  as  the 
heaviness  of  the  rain,  the  direction  and  force 
of  the  wind,  &c.,  appear  to  be  more  impor- 
tant in  determining  the  quantity  of  the  earth 
which  flows  down  a slope  than  its  angle. 
Thus  with  four  castings  on  my  lawn  (in- 
cluded in  the  above  eleven)  where  the  mean 
slope  was  70  19',  the  difference  in  the 
amount  of  earth  above  and  below  the  bur- 
rows was  greater  than  with  three  other  cast- 


Chap.  VI.  AIDED  BY  WORMS.  269 

ings  on  the  same  lawn  where  the  mean  slope 
was  120  5'. 

We  may,  however,  take  the  above  eleven 
cases,  which  are  accurate  as  far  as  they  go, 
and  calculate  the  weight  of  the  ejected  earth 
which  annually  flows  down  a slope  having  a 
mean  inclination  of  90  26'.  This  was  done 
by  my  son  George.  It  has  been  shown  that 
almost  exactly  two-thirds  of  the  ejected  earth 
is  found  below  the  mouth  of  the  burrow  and 
one-third  above  it.  Now  if  the  two-thirds 
which  is  below  the  hole  be  divided  into  two 
equal  parts,  the  upper  half  of  this  two-thirds 
exactly  counterbalances  the  one-third  which  is 
above  the  hole,  so  that  as  far  as  regards  the 
one-third  above  and  the  upper  half  of  the  two- 
thirds  below,  there  is  no  flow  of  earth  down 
the  hill-side.  The  earth  constituting  the  lower 
half  of  the  two-thirds  is,  however,  displaced 
through  distances  which  are  different  for 
every  part  of  it,  but  which  may  be  represented 
by  the  distance  between  the  middle  point  of 
the  lower  half  of  the  two-thirds  and  the  hole. 
So  that  the  average  distance  of  displacement 
is  a half  of  the  whole  length  of  the  worm-cast- 


27  o 


DENUDATION  OF  THE  LAND  Chap.  VI. 


ing.  Now  the  average  length  of  ten  out  of 
the  above  eleven  castings  was  2.03  inches,  and 
half  of  this  we  may  take  as  being  one  inch. 
It  may  therefore  be  concluded  that  one-third 
of  the  whole  earth  brought  to  the  surface  was 
in  these  cases  carried  down  the  slope  through 
one  inch. 

It  was  shown  in  the  third  chapter  that  on 
Leith  Hill  Common,  dry  earth  weighing  at 
least  7.453  lbs.  was  brought  up  by  worms  to 
the  surface  on  a square  yard  in  the  course  of  a 
year.  If  a square  yard  be  drawn  on  a hill-side 
with  two  of  its  sides  horizontal,  then  it  is  clear 
that  only  part  of  the  earth  brought  up  on 
that  square  yard  would  be  near  enough  to  its 
lower  side  to  cross  it,  supposing  the  displace- 
ment of  the  earth  to  be  through  one  inch. 
But  it  appears  that  only  J of  the  earth  brought 
up  can  be  considered  to  flow  downwards; 
hence  g of  -^V  or  of  7.453  lbs.  will  cross  the 
lower  side  of  our  square  yard  in  a year.  Now 
T-g-g-  of  7.453  lbs.  is  1. 1 oz.  Therefore  1.1  oz. 
of  dry  earth  will  annually  cross  each  linear 
yard  running  horizontally  along  a slope  having 
the  above  inclination;  or  very  nearly  7 lbs. 


Chap.  VI. 


AIDED  BY  WORMS. 


271 


will  annually  cross  a horizontal  line,  100  yards 
in  length,  on  a hill-side  having  this  inclination. 

A more  accurate,  though  still  very  rough, 
calculation  can  be  made  of  the  bulk  of  earth, 
which  in  its  natural  damp  state  annually  flows 
down  the  same  slope  over  a yard-line  drawn 
horizontally  across  it.  From  the  several  cases 
given  in  the  third  chapter,  it  is  known  that  the 
castings  annually  brought  to  the  surface  on 
a square  yard,  if  uniformly  spread  out  would 
form  a layer  .2  of  an  inch  in  thickness:  it  there- 
fore follows  by  a calculation  similar  to  the  one 
already  given,  that  ^ of  .2  X 36,  or  2.4  cubic 
inches  of  damp  earth  will  annually  cross  a hori- 
zontal line  one  yard  in  length  on  a hill-side 
with  the  above  inclination.  This  bulk  of  damp 
castings  was  found  to  weigh  1.85  oz.  There- 
fore 11.56  lbs.  of  damp  earth,  instead  of  7 lbs. 
of  dry  earth  as  by  the  former  calculation,  would 
annually  cross  a line  100  yards  in  length  on 
our  inclined  surface. 

In  these  calculations  it  has  been  assumed 
that  the  castings  flow  a short  distance  down- 
wards during  the  whole  year,  but  this  occurs 
only  with  those  ejected  during  or  shortly  be- 


272  DENUDATION  OF  THE  LAND  Chap.  VI. 

fore  rain;  so  that  the  above  results  are  thus 
far  exaggerated.  On  the  other  hand,  during 
rain  much  of  the  finest  earth  is  washed  to  a 
considerable  distance  from  the  castings,  even 
where  the  slope  is  an  extremely  gentle  one, 
and  is  thus  wholly  lost  as  far  as  the  above 
calculations  are  concerned.  Castings  ejected 
during  dry  weather  and  which  have  set  hard, 
lose  in  the  same  manner  a considerable  quan- 
tity of  fine  earth.  Dried  castings,  moreover, 
are  apt  to  disintegrate  into  little  pellets,  which 
often  roll  or  are  blown  down  any  inclined  sur- 
face. Therefore  the  above  result,  namely  that 
2.4  cubic  inches  of  earth  (weighing  1.85  oz. 
whilst  damp)  annually  crosses  a yard-line  of 
*■’  the  specified  kind,  is  probably  not  much  if  at  all 
exaggerated. 

This  amount  is  small;  but  we  should  bear 
in  mind  how  many  brainching  valleys  inter- 
sect most  countries,  the  whole  length  of  which 
must  be  very  great;  and  that  earth  is  steadily 
travelling  down  both  turf-covered  sides  of  each 
valley.  For  every  100  yards  in  length  in  a 
valley  with  sides  sloping  as  in  the  foregoing 
cases,  480  cubic  inches  of  damp  earth,  weigh- 


Chap.  VI. 


AIDED  BY  WORMS. 


273 


in g above  23  pounds,  will  annually  reach  the 
bottom.  Here  a thick  bed  of  alluvium  will 
accumulate,  ready  to  be  washed  away  in  the 
course  of  centuries,  as  the  stream  in  the  middle 
meanders  from  side  to  side. 

If  it  could  be  shown  that  worms  generally 
excavate  their  burrows  at  right  angles  to  an 
inclined  surface,  and  this  would  be  their  short- 
est course  for  bringing  up  earth  from  beneath, 
then  as  the  old  burrows  collapsed  from  the 
weight  of  the  superincumbent  soil,  the  collaps- 
ing would  inevitably  cause  the  whole  bed  of 
vegetable  mould  to  sink  or  slide  slowly  down 
the  inclined  surface.  But  to  ascertain  the  di- 
rection of  many  burrows  was  found  too  diffi- 
cult and  troublesome.  A straight  piece  of 
wire  was,  however,  pushed  into  twenty-five 
burrows  on  several  sloping  fields,  and  in  eight 
cases  the  burrows  were  nearly  at  right  angles 
to  the  slope;  whilst  in  the  remaining  cases  they 
were  indifferently  directed  at  various  angles, 
either  upwards  or  downwards  with  respect  to 
the  slope. 

In  countries  where  the  rain  is  very  heavy, 
as  in  the  tropics,  the  castings  appear,  as  might 


274 


DENUDATION  OF  THE  LAND  Chap.  VI. 


have  been  expected,  to  be  washed  down  in  a 
greater  degree  than  in  England.  Mr.  Scott 
informs  me  that  near  Calcutta  the  tall  colum- 
nar castings  (previously  described),  the  diam- 
eter of  which  is  usually  between  I and  i-J  inch, 
subside  on  a level  surface,  after  heavy  rain, 
into  almost  circular,  thin,  flat  discs,  between  3 
and  4 and  sometimes  5 inches  in  diameter. 
Three  fresh  castings,  which  had  been  ejected 
in  the  Botanic  Gardens  “ on  a slightly  inclined, 
grass-covered,  artificial  bank  of  loamy  clay,” 
were  carefully  measured,  and  had  a mean 
height  of  2.17,  and  a mean  diameter  of  1.43 
inches;  these  after  heavy  rain,  formed  elon- 
gated patches  of  earth,  with  a mean  length  in 
the  direction  of  the  slope  of  5.83  inches.  As 
the  earth  had  spread  very  little  up  the  slope, 
a large  part,  judging  from  the  original  diam- 
eter of  these  castings,  must  have  flowed  bodily 
downwards  about  4 inches.  Moreover  some 
of  the  finest  earth  of  which  they  were  com- 
posed must  have  been  washed  completely  away 
to  a still  greater  distance.  In  drier  sites  near 
Calcutta,  a species  of  worm  ejects  its  castings, 
not  in  vermiform  masses,  but  in  little  pellets 


Chap.  VI. 


AIDED  BY  WORMS. 


275 


of  varying  sizes:  these  are  very  numerous  in 
some  places,  and  Mr.  Scott  says  that  they  “ are 
washed  away  by  every  shower.” 


I was  led  to  believe  that  a considerable 
quantity  of  fine  earth  is  washed  quite  away 
from  castings  during  rain,  from  the  surfaces 
of  old  ones  being  often  studded  with  coarse 
particles.  Accordingly  a little  fine  precipitated 
chalk,  moistened  with  saliva  or  gum-water,  so 
as  to  be  slightly  viscid  and  of  the  same  con- 
sistence as  a fresh  casting,  was  placed  on  the 
summits  of  several  castings  and  gently  mixed 
with  them.  These  castings  were  then  watered 
through  a very  fine  rose,  the  drops  from  which 
were  closer  together  than  those  of  rain,  but 
not  nearly  so  large  as  those  in  a thunder  storm; 
nor  did  they  strike  the  ground  with  nearly  so 
much  force  as  drops  during  heavy  rain.  A 
casting  thus  treated  subsided  with  surprising 
slowness,  owing  as  I suppose  to  its  viscidity. 
It  did  not  flow  bodily  down  the  { 


at  an  angle  of  160  20';  nevertheless  many  par- 
ticles of  the  chalk  were  found  three  inches  bel- 
low the  casting.  The  experiment  was  repeated 


surface  of  the  lawn,  which  was 


276  DENUDATION  OF  THE  LAND  Chap.  VI. 

on  three  other  castings  on  different  parts  of 
the  lawn,  which  sloped  at  20  30',  30  and  6°; 
and  particles  of  chalk  could  be  seen  between 
4 and  5 inches  below  the  casting;  and  after 
the  surface  had  become  dry,  particles  were 
found  in  two  cases  at  a distance  of  5 and  6 
inches.  Several  other  castings  with  precipi- 
tated chalk  placed  on  their  summits  were  left 
to  the  natural  action  of  the  rain.  In  one  case, 
after  rain  which  was  not  heavy,  the  casting 
was  longitudinally  streaked  with  white.  In 
two  other  cases  the  surface  of  the  ground  was 
rendered  somewhat  white  for  a distance  of 
one  inch  from  the  casting;  and  some  soil  col- 
lected at  a distance  of  2\  inches,  where  the 
slope  was  70,  effervesced  slightly  when  placed 
in  acid.  After  one  or  two  weeks,  the  chalk 
was  wholly  or  almost  wholly  washed  away 
from  all  the  castings  on  which  it  had  been 
placed,  and  these  had  recovered  their  natural 
colour. 

It  may  be  here  remarked  that  after  very 
heavy  rain  shallow  pools  may  be  seen  on  level 
or  nearly  level  fields,  where  the  soil  is  not  very 
porous,  and  the  water  in  them  is  often  slightly 


Chap.  VI. 


AIDED  BY  WORMS. 


2 77 


muddy;  when  such  little  pools  have  dried,  the 
leaves  and  blades  of  grass  at  their  bottoms  are 
generally  coated  with  a thin  layer  of  mud. 
This  mud  I believe  is  derived  in  large  part 
from  recently  ejected  castings. 

Dr.  King  informs  me  that  the  majority  of 
the  before  described  gigantic  castings,  which 
he  found  on  a fully  exposed,  bare,  gravelly 
knoll  on  the  Nilgiri  Mountains  in  India,  had 
been  more  or  less  weathered  by  the  previous 
north-east  monsoon;  and  most  of  them  pre- 
sented a subsided  appearance.  The  worms 
here  eject  their  castings  only  during  the  rainy 
season;  and  at  the  time  of  Dr.  King's  visit  no 
rain  had  fallen  for  no  days.  He  carefully  ex- 
amined the  ground  between  the  place  where 
these  huge  castings  lay,  and  a little  water- 
course at  the  base  of  the  knoll,  and  nowhere 
was  there  any  accumulation  of  fine  earth,  such 
as  would  necessarily  have  been  left  by  the  dis- 
integration of  the  castings  if  they  had  not  been 
wholly  removed.  He  therefore  has  no  hesita- 
tion in  asserting  that  the  whole  of  these  huge 
castings  are  annually  washed  during  the  two 
monsoons  (when  about  100  inches  of  rain  fall) 


«/ 


2 78  DENUDATION  OF  THE  LAND  Chap.  VI. 

into  the  little  water-course,  and  thence  into  the 
plains  lying  below  at  a depth  of  3000  or  4000 
feet. 

Castings  ejected  before  or  during  dry 
Weather  become  hard,  sometimes  surprisingly 
hard,  from  the  particles  of  earth  having  been 
cemented  together  by  the  intestinal  secretions. 
Frost  seems  to  be  less  effective  in  their  disin- 
tegration than  might  have  been  expected. 
Nevertheless  they  readily  disintegrate  into 
small  pellets,  after  being  alternately  moistened 
with  rain  and  again  dried.  Those  which  have 
flowed  during  rain  down  a slope,  disintegrate 
in  the  same  manner.  Such  pellets  often  roll  a 
little  down  any  sloping  surface;  their  descent 
being  sometimes  much  aided  by  the  wind. 
The  whole  bottom  of  a broad  dry  ditch  in  my 
grounds,  where  there  were  very  few  fresh  cast- 
ings, was  completely  covered  with  these  pellets 
or  disintegrated  castings,  which  had  rolled 
down  the  steep  sides  inclined  at  an  angle 
of  270. 

Near  Nice,  in  places  where  the  great  cylin- 
drical castings,  previously  described,  abound, 
the  soil  consists  of  very  fine  arenaceo-calcare- 


Chap.  VI. 


AIDED  BY  WORMS. 


279 


ous  loam;  and  Dr.  King  informs  me  that  these 
castings  are  extremely  liable  to  crumble  during 
dry  weather  into  small  fragments,  which  are 
soon  acted  on  by  rain,  and  then  sink  down  so 
as  to  be  no  longer  distinguishable  from  the 
surrounding  soil.  He  sent  me  a mass  of  such 
disintegrated  castings,  collected  on  the  top  of 
a bank,  where  none  could  have  rolled  dowrt 
from  above.  They  must  have  been  ejected 
within  the  previous  five  or  six  months,  but 
they  now  consisted  of  more  or  less  rounded 
fragments  of  all  sizes,  from  f of  an  inch  in 
diameter  to  minute  grains  and  mere  dust.  Dr. 
King  witnessed  the  crumbling  process  whilst 
drying  some  perfect  castings,  which  he  after- 
wards sent  me.  Mr.  Scott  also  remarks  on  the 
crumbling  of  the  castings  near  Calcutta  and  on 
the  mountains  of  Sikkim  during  the  hot  and 
dry  season. 

When  the  castings  near  Nice  had  been 
ejected  on  an  inclined  surface,  the  disinte- 
grated fragments  rolled  downwards,  without 
losing  their  distinctive  shape;  and  in  some 
places  could  “ be  collected  in  basketfuls.”  Dr. 
King  observed  a striking  instance  of  this  fact 


280 


DENUDATION  TO  LAND 


Chap.  VI. 


on  the  Corniche  road,  where  a drain,  about 
2.\  feet  wide  and  9 inches  deep,  had  been  made 
to  catch  the  surface  drainings  from  the  adjoin- 
ing hill-side.  The  bottom  of  this  drain  was 
covered  for  a distance  of  several  hundred  yards, 
to  a depth  of  from  i|  to  3 inches,  by  a layer 
of  broken  castings,  still  retaining  their  charac- 
teristic shape.  Nearly  all  these  innumerable 
fragments  had  rolled  down  from  above,  for  ex- 
tremely few  castings  had  been  ejected  in  the 
drain  itself.  The  hill-side  was  steep,  but  varied 
much  in  inclination,  which  Dr.  King  estimated 
at  from  30°  to  6o°  with  the  horizon.  He 
climbed  up  the  slope,  and  “ found  every  here 
and  there  little  embankments,  formed  by  frag- 
ments of  the  castings  that  had  been  arrested 
in  their  downward  progress  by  irregularities  of 
the  surface,  by  stones,  twigs,  &c.  One  little 
group  of  plants  of  Anemone  hortensis  had  acted 
in  this  manner,  and  quite  a small  bank  of  soil 
had  collected  round  it.  Much  of  this  soil  had 
crumbled  down,  but  a great  deal  of  it  still  re- 
tained the  form  of  castings.”  Dr.  King  dug 
up  this  plant,  and  was  struck  with  the  thick- 
ness of  the  soil  which  must  have  recently  accu- 


Chap.  VI. 


LEDGES  ON  HILL-SIDES. 


28l 


mulated  over  the  crown  of  the  rhizoma,  as 
shown  by  the  length  of  the  bleached  petioles, 
in  comparison  with  those  of  other  plants  of 
the  same  kind,  where  there  had  been  no  such 
accumulation.  The  earth  thus  accumulated 
had  no  doubt  been  secured  (as  I have  every- 
where seen)  by  the  smaller  roots  of  the  plants. 
After  describing  this  and  other  analogous 
cases,  Dr.  King  concludes:  “ I can  have  no 
doubt  that  worms  help  greatly  in  the  process 
of  denudation.” 

Ledges  of  earth  on  steep  hill-sides. — Little 
horizontal  ledges,  one  above  another,  have 
been  observed  on  steep  grassy  slopes  in  many 
parts  of  the  world.  Their  formation  has  been 
attributed  to  animals  travelling  repeatedly 
along  the  slope  in  the  same  horizontal  lines 
while  grazing,  and  that  they  do  thus  move  and 
use  the  ledges  is  certain;  but  Professor  Hens- 
low  (a  most  careful  observer)  told  Sir  J.  Hook- 
er that  he  was  convinced  that  this  was  not  the 
sole  cause  of  their  formation.  Sir  J.  Hooker 
saw  such  ledges  on  the  Himalayan  and  Atlas 
ranges,  where  there  were  no  domesticated  ani- 
mals and  not  many  wild  ones;  but  these  latter 
19 


282 


DENUDATION  TO  LAND 


Chap.  VI. 


would,  it  is  probable,  use  the  ledges  at  night 
while  grazing  like  our  domesticated  animals. 
A friend  observed  for  me  the  ledges  on  the 
Alps  of  Switzerland,  and  states  that  they  ran 
at  3 or  4 feet  one  above  the  other  and  were 
about  a foot  in  breadth.  They  had  been  deep- 
ly pitted  by  the  feet  of  grazing  cows.  Similar 
ledges  were  observed  by  the  same  friend  on 
our  Chalk  downs,  and  on  an  old  talus  of  chalk- 
fragments  (thrown  out  of  a quarry)  which  had 
become  clothed  with  turf. 

My  son  Francis  examined  a Chalk  escarp- 
ment near  Lewes;  and  here  on  a part  which 
was  very  steep,  sloping  at  40°  with  the  hori- 
zon, about  30  flat  ledges  extended  horizontally 
for  more  than  100  yards,  at  an  average  distance 
of  about  20  inches,  one  beneath  the  other. 
They  were  from  9 to  10  inches  in  breadth. 
When  viewed  from  a distance  they  presented  a 
striking  appearance,  owing  to  their  parallel- 
ism; but  when  examined  closely,  they  were 
seen  to  be  somewhat  sinuous,  and  one  often 
ran  into  another,  giving  the  appearance  of  one 
ledge  having  forked  into  two.  They  are 
formed  of  light-coloured  earth,  which  on  the 


Chap.  VI. 


LEDGES  ON  HILL-SIDES. 


283 


outside,  where  thickest,  was  in  one  case  9 
inches,  and  in  another  case  between  6 and  7 
inches  in  thickness.  Above  the  ledges,  the 
thickness  of  the  earth  over  the  chalk  was  in 
the  former  case  4 and  in  the  latter  only  3 
inches.  The  grass  grew  more  vigorously  on 
the  outer  edges  of  the  ledges  than  on  any 
other  part  of  the  slope,  and  here  formed  a 
tufted  fringe.  Their  middle  part  was  bare,  but 
whether  this  had  been  caused  by  the  trampling 
of  sheep,  which  sometimes  frequent  the  ledges, 
my  son  could  not  ascertain.  Nor  could  he 
feel  sure  how  much  of  the  earth  on  the  middle 
and  bare  parts,  consisted  of  disintegrated 
worm-castings  which  had  rolled  down  from 
above;  but  he  felt  convinced  that  some  had 
thus  originated;  and  it  was  manifest  that  the 
ledges  with  their  grass-fringed  edges  would 
arrest  any  small  object  rolling  down  from 
above. 

^At  one  end  or  side  of  the  bank  bearing 
these  ledges,  the  surface  consisted  in  parts  of 
bare  chalk,  and  here  the  ledges  were  very  ir- 
regular. At  the  other  end  of  the  bank,  the 
slope  suddenly  became  less  steep,  and  here  the 


284  DENUDATION  TO  LAND  Chap.  VI. 

ledges  ceased  rather  abruptly;  but  little  em- 
bankments only  a foot  or  two  in  length  were 
still  present.  The  slope  became  steeper  lower 
down  the  hill,  and  the  regular  ledges  then  re- 
appeared. Another  of  my  sons  observed,  on 
the  inland  side  of  Beachy  Head,  where  the 
surface  sloped  at  about  250,  many  short  little 
embankments  like  those  just  mentioned.  They 
extended  horizontally  and  were  from  a few 
inches  to  two  or  three  feet  in  length.  They 
supported  tufts  of  grass  growing  vigorously. 
The  average  thickness  of  the  mould  of  which 
they  were  formed,  taken  from  nine  measure- 
ments, was  4.5  inches;  while  that  of  the  mould 
above  and  beneath  them  was  on  an  average 
only  3.2  inches,  and  on  each  side,  on  the  same 
level,  3.1  inches.  On  the  upper  parts  of  the 
slope,  these  embankments  showed  no  signs  of 
having  been  trampled  on  by  sheep,  but  in  the 
lower  parts  such  signs  were  fairly  plain.  No 
long  continuous  ledges  had  here  been  formed. 

If  the  little  embankments  above  the  Cor- 
niche  road,  which  Dr.  King  saw  in  the  act  of 
formation  by  the  accumulation  of  disintegrated 
and  rolled  worm-castings,  were  to  become  con- 


Chap.  VI.  LEDGES  ON  HILL-SIDES.  285 

fluent  along  horizontal  lines,  ledges  would  be 
formed.  Each  embankment  would  tend  to  ex- 
tend laterally  by  the  lateral  extension  of  the 
arrested  castings;  and  animals  grazing  on  a 
steep  slope  would  almost  certainly  make  use 
of  every  prominence  at  nearly  the  same  level, 
and  would  indent  the  turf  between  them;  and 
such  intermediate  indentations  would  again 
arrest  the  castings.  An  irregular  ledge  when 
once  formed  would  also  tend  to  become  more 
regular  and  horizontal  by  some  of  the  castings 
rolling  laterally  from  the  higher  to  the  lower 
parts,  which  would  thus  be  raised.  Any  pro- 
jection beneath  a ledge  would  not  afterwards 
receive  disintegrated  matter  from  above,  and 
would  tend  to  be  obliterated  by  rain  and  other 
atmospheric  agencies.  There  is  some  analogy 
between  the  formation,  as  here  supposed,  of 
these  ledges,  and  that  of  the  ripples  of  wind- 
drifted  sand  as  described  by  Lyell.* 

The  steep,  grass-covered  sides  of  a moun- 
tainous valley  in  Westmoreland,  called  Grise- 
dale,  was  marked  in  many  places  with  innumer- 
able, almost  horizontal,  little  ledges,  or  rather 

* “Elements  of  Geology,”  1865,  p.  20. 


286 


DENUDATION  OF  THE  LAND.  Chap.  VI. 


lines  of  miniature  cliffs.  Their  formation  was 
in  no  way  connected  with  the  action  of  worms, 
for  castings  could  not  anywhere  be  seen  (and 
their  absence  is  an  inexplicable  fact)  although 
the  turf  lay  in  many  places  over  a considerable 
thickness  of  boulder-clay  and  moraine  rubbish. 
Nor,  as  far  as  I can  judge,  was  the  formation 
of  these  little  cliffs  at  all  closely  connected 
with  the  trampling  of  cows  or  sheep.  It  ap- 
peared as  if  the  whole  superficial,  somewhat 
argillaceous  earth,  while  partially  held  together 
by  the  roots  of  the  grasses,  had  slided  a little 
way  down  the  mountain  sides;  and  in  thus 
sliding,  had  yielded  and  cracked  in  horizontal 
lines,  transversely  to  the  slope. 

Castings  blown  to  leeward  by  the  wind . — We 
have  seen  that  moist  castings  flow,  and  that 
disintegrated  castings  roll  down  any  inclined 
surface;  and  we  shall  now  see  that  castings, 
recently  ejected  on  level  grass-covered  sur- 
faces, are  blown  during  gales  of  wind  accom- 
panied by  rain  to  leeward.  This  has  been  ob- 
served by  me  many  times  on  many  fields 
during  several  successive  years.  After  such 


Chap.  VI.  CASTINGS  BLOWN  TO  LEEWARD.  287 

gales,  the  castings  present  a gently  inclined 
and  smooth,  or  sometimes  furrowed,  surface 
to  windward,  while  they  are  steeply  inclined 
or  precipitous  to  leeward,  so  that  they  resem- 
ble on  a miniature  scale  glacier-ground  hillocks 
of  rock.  They  are  often  cavernous  on  the  lee- 
ward side,  from  the  upper  part  having  curled 
over  the  lower  part.  During  one  unusually 
heavy  south-west  gale  with  torrents  of  rain, 
many  castings  were  wholly  blown  to  leeward, 
so  that  the  mouths  of  the  burrows  were  left 
naked  and  exposed  on  the  windward  side.  Re- 
cent castings  naturally  flow  down  an  inclined 
surface,  but  on  a grassy  field,  which  sloped  be- 
tween io°  and  1 50,  several  were  found  after  a 
heavy  gale  blown  up  the  slope.  This  like- 
wise occurred  on  another  occasion  on  a part 
of  my  lawn  where  the  slope  was  somewhat  less. 
On  a third  occasion,  the  castings  on  the  steep, 
grass-covered  sides  of  a valley,  down  which  a 
gale  had  blown,  were  directed  obliquely  in- 
stead of  straight  down  the  slope;  and  this  was 
obviously  due  to  the  combined  action  of  the 
wind  and  gravity.  Four  castings  on  my  lawn, 
where  the  downward  inclination  was  o°  45',  i°, 


288 


DENUDATION  OF  THE  LAND.  Chap.  VI. 


3°  and  30  30'  (mean  2°  45')  towards  the  north- 
east, after  a heavy  south-west  gale  with  rain, 
were  divided  across  the  mouths  of  the  bur- 
rows and  weighed  in  the  manner  formerly  de- 
scribed. The  mean  weight  of  the  earth  below 
the  mouths  of  burrows  and  to  leeward,  was  to 
that  above  the  mouths  and  on  the  windward 
side  as  2§  to  1;  whereas  we  have  seen  that 
with  several  castings  which  had  flowed  down 
slopes  having  a mean  inclination  of  90  26',  and 
with  three  castings  where  the  inclination  was 
above  120,  the  proportional  weight  of  the 
earth  below  to  that  above  the  burrows  was  as 
only  2 to  1.  These  several  cases  show  how 
efficiently  gales  of  wind  accompanied  by  rain 
act  in  displacing  recently-ejected  castings. 
-We  may  therefore  conclude  that  even  a mod- 
erately strong  wind  will  produce  some  slight 
effect  on  them. 

Dry  and  indurated  castings,  after  their  dis- 
integration into  small  fragments  or  pellets,  are 
sometimes,  probably  often,  blown  by  a strong 
wind  to  leeward.  This  was  observed  on  four 
occasions,  but  I did  not  sufficiently  attend  to 
this  point.  One  old  casting  on  a gently  slop- 


Chap.  VI.  CASTINGS  BLOWN  TO  LEEWARD.  289 

in g bank  was  blown  quite  away  by  a strong 
south-west  wind.  Dr.  King  believes  that  the 
wind  removes  the  greater  part  of  the  old  crum- 
bling castings  near  Nice.  Several  old  castings 
on  my  lawn  were  marked  with  pins  and  pro- 
tected from  any  disturbance.  They  were  ex- 
amined after  an  interval  of  10  weeks,  during 
which  time  the  weather  had  been  alternately 
dry  and  rainy.  Some,  which  were  of  a yel- 
lowish colour  had  been  washed  almost  com- 
pletely away,  as  could  be  seen  by  the  colour 
of  the  surrounding  ground.  Others  had  com- 
pletely disappeared,  and  these  no  doubt  had 
been  blown  away.  Lastly,  others  still  re- 
mained and  would  long  remain,  as  blades  of 
grass  had  grown  through  them.  On  poor 
pasture-land,  which  has  never  been  rolled  and 
has  not  been  much  trampled  on  by  animals,  the 
whole  surface  is  sometimes  dotted  with  little 
pimples,  through  and  on  which  grass  grows; 
and  these  pimples  consist  of  old  worm-castings. 

In  all  the  many  observed  cases  of  soft  cast- 
ings blown  to  leeward,  this  had  been  effected 
by  strong  winds  accompanied  by  rain.  As 
such  winds  in  England  generally  blow  from 


290 


DENUDATION  OF  THE  LAND.  Chap.  VI. 


the  south  and  south-west,  earth  must  on  the 
whole  tend  to  travel  over  our  fields  in  a north 
and  north-east  direction.  This  fact  is  inter- 
esting, because  it  might  be  thought  that  none 
could  be  removed  from  a level,  grass-covered 
surface  by  any  means.  In  thick  and  level 
woods,  protected  from  the  wind,  castings  will 
never  be  removed  as  long  as  the  wood  lasts; 
and  mould  will  here  tend  to  accumulate  to  the 
depth  at  which  worms  can  work.  I tried  to 
procure  evidence  as  to  how  much  mould  is 
blown,  whilst  in  the  state  of  castings,  by  our 
wet  southern  gales  to  the  north-east,  over 
open  and  flat  land,  by  looking  to  the  level  o£ 
the  surface  on  opposite  sides  of  old  trees  and 
hedge-rows;  but  I failed  owing  to  the  unequal 
growth  of  the  roots  of  trees  and  to  most  pas- 
ture-land having  been  formerly  ploughed. 

On  an  open  plain  near  Stonehenge,  there 
exist  shallow  circular  trenches,  with  a low  em- 
bankment outside,  surrounding  level  spaces  50 
yards  in  diameter.  These  rings  appear  very 
ancient,  and  are  believed  to  be  contempora- 
neous with  the  Druidical  stones.  Castings 
ejected  within  these  circular  spaces,  if  blown 


Chap.  VI.  CASTINGS  BLOWN  TO  LEEWARD.  2gi 

to  the  north-east  by  south-west  winds  would 
form  a layer  of  mould  within  the  trench  thicker 
on  the  north-eastern  than  on  any  other  side. 
But  the  site  was  not  favourable  for  the  action 
of  worms,  for  the  mould  over  the  surrounding 
Chalk  formation  with  flints,  was  only  3.37 
inches  in  thickness,  from  a mean  of  six  ob- 
servations made  at  a distance  of  10  yards  out- 
side the  embankment.  The  thickness  of  the 
mould  within  two  of  the  circular  trenches  was 
measured  every  5 yards  all  round,  on  the  inner 
sides  near  the  bottom.  My  son  Horace  pro- 
tracted these  measurements  on  paper;  and 
though  the  curved  line  representing  the  thick- 
ness of  the  mould  was  extremely  irregular,  yet 
in  both  diagrams  it  could  be  seen  to  be  thicker 
on  the  north-eastern  side  than  elsewhere. 
When  a mean  of  all  the  measurements  in  both 
the  trenches  was  laid  down  and  the  line 
smoothed,  it  was  obvious  that  the  mould  was 
thickest  in  the  quarter  of  the  circle  between 
north-west  and  north-east;  and  thinnest  in  the 
quarter  between  south-east  and  south-west,  es- 
pecially at  this  latter  point.  Besides  the  fore- 
going measurements,  six  others  were  taken 


292 


DENUDATION  OF  THE  LAND.  Chap.  VI. 


near  together  in  one  of  the  circular  trenches, 
on  the  north-east  side;  and  the  mould  here 
had  a mean  thickness  of  2.29  inches;  while  the 
mean  of  six  other  measurements  on  the  south- 
west side  was  only  1.46  inches.  These  obser- 
vations indicate  that  the  castings  had  been 
blown  by  the  south-west  winds  from  the  cir- 
cular enclosed  space  into  the  trench  on  the 
north-east  side;  but  many  more  measurements 
in  other  analogous  cases  would  be  requisite 
for  a trustworthy  result. 

The  amount  of  fine  earth  brought  to  the 
surface  under  the  form  of  castings,  and  after- 
wards transported  by  the  winds  accompanied 
by  rain,  or  that  which  flows  and  rolls  down 
an  inclined  surface,  no  doubt  is  small  in  the 
course  of  a few  scores  of  years;  for  otherwise 
all  the  inequalities  in  our  pasture-fields  would 
be  smoothed  within  a much  shorter  period 
than  appears  to  be  the  case.  But  the  amount 
which  is  thus  transported  in  the  course  of 
thousands  of  years  cannot  fail  to  be  consider- 
able and  deserves  attention.  E.  de  Beaumont 
looks  at  the  vegetable  mould  which  every- 
where covers  the  land  as  a fixed  line  or  zero, 


Chap.  VI. 


ANCIENT  MOUNDS. 


293 


from  which  the  amount  of  denudation  may  be 
measured.*  He  ignores  the  continued  forma- 
tion of  fresh  mould  by  the  disintegration  of 
the  underlying  rocks  and  fragments  of  rock; 
and  it  is  curious  to  find  how  much  more  philo- 
sophical were  the  views,  maintained  long  ago, 
by  Playfair,  who,  in  1802,  wrote,  “ In  the  per- 
manence of  a coat  of  vegetable  mould  on  the 
surface  of  the  earth,  we  have  a demonstrative 
proof  of  the  continued  destruction  of  the 
rocks.”  * 

Ancient  encampments  and  tumuli. — E.  de 
Beaumont  adduces  the  present  state  of  many 
ancient  encampments  and  tumuli  and  of  old 
ploughed  fields,  as  evidence  that  the  surface 
of  the  land  undergoes  hardly  any  degradation. 
But  it  does  not  appear  that  he  ever  examined 
the  thickness  of  the  mould  over  different  parts 
of  such  old  remains.  He  relies  chiefly  on  in- 
direct, but  apparently  trustworthy,  evidence 
that  the  slopes  of  the  old  embankments  are  the 

* “ Le£ons  de  Geologie  pratique,”  1845  ; cinqui&me  Le5on. 
All  Elie  de  Beaumont’s  arguments  are  admirably  controverted 
by  Prof.  A.  Geikie  in  his  essay  in  “Transact.  Geolog.  Soc.  of 
Glasgow,”  vol.  iii.  p.  153,  1868. 

f “ Illustrations  of  the  Huttonian  Theory  of  the  Earth,”  p. 
107. 


294 


DENUDATION  OF  THE  LAND.  Chap.  VI. 


same  as  they  originally  were;  and  it  is  obvious 
that  he  could  know  nothing  about  their  origi- 
nal heights.  In  Knole  Park  a mound  had 
been  thrown  up  behind  the  rifle-targets,  which 
appeared  to  have  been  formed  of  earth  origi- 
nally supported  by  square  blocks  of  turf.  The 
sides  sloped,  as  nearly  as  I could  estimate  them, 
at  an  angle  of  45 ° or  50°  with  the  horizon, 
and  they  were  covered,  especially  on  the  north- 
ern side,  with  long  coarse  grass,  beneath  which 
many  worm-castings  were  found.  These  had 
flowed  bodily  downwards,  and  others  had 
rolled  down  as  pellets.  Hence  it  is  certain 
that  as  long  as  a mound  of  this  kind  is  ten- 
anted by  worms,  its  height  will  be  continually 
lowered.  The  fine  earth  which  flows  or  rolls 
down  the  sides  of  such  a mound  accumulates 
at  its  base  in  the  form  of  a talus.  A bed,  even 
a very  thin  bed,  of  fine  earth  is  eminently  fa- 
vourable for  worms;  so  that  a greater  number 
of  castings  would  tend  to  be  ejected  on  a talus 
thus  formed  than  elsewhere;  and  these  would 
be  partially  washed  away  by  every  heavy 
shower  and  be  spread  over  the  adjoining  level 
ground.  The  final  result  would  be  the  lower- 


Chap.  VI.  ANCIENTLY  PLOUGHED  FIELDS.  295 

in g of  the  whole  mound,  whilst  the  inclina- 
tion of  the  sides  would  not  be  greatly  lessened. 
The  same  result  would  assuredly  follow  with 
ancient  embankments  and  tumuli  ; except 
where  they  had  been  formed  of  gravel  or  of 
nearly  pure  sand,  as  such  matter  is  unfavour- 
able for  worms.  Many  old  fortifications  and 
tumuli  are  believed  to  be  at  least  2000  years 
old;  and  we  should  bear  in  mind  that  in  many 
places  about  one  inch  of  mould  is  brought  to 
the  surface  in  5 years  or  two  inches  in  10  years. 
Therefore  in  so  long  a period  as  2000  years, 
a large  amount  of  earth  will  have  been  repeat- 
edly brought  to  the  surface  on  most  old  em- 
bankments and  tumuli,  especially  on  the  talus 
round  their  bases,  and  much  of  this  earth  will 
have  been  washed  completely  away.  We  may 
therefore  conclude  that  all  ancient  mounds, 
when  not  formed  of  materials  unfavourable  to 
worms,  will  have  been  somewhat  lowered  in 
the  course  of  centuries,  although  their  inclina- 
tions may  not  have  been  greatly  changed. 

Fields  formerly  ploughed. — From  a very  re- 
mote period  and  in  many  countries,  land  has 
been  ploughed,  so  that  convex  beds,  called 


296  DENUDATION  OF  THE  LAND.  Ciiap.  VI. 

crowns  or  ridges,  usually  about  8 feet  across 
and  separated  by  furrows,  have  been  thrown 
up.  The  furrows  are  directed  so  as  to  carry  off 
the  surface  water.  In  my  attempts  to  ascer- 
tain how  long  a time  these  crowns  and  furrows 
last,  when  ploughed  land  has  been  converted 
into  pasture,  obstacles  of  many  kinds  were  en- 
countered. It  is  rarely  known  when  a field 
was  last  ploughed;  and  some  fields  which  were 
thought  to  have  been  in  pasture  from  time 
immemorial  were  afterwards  discovered  to 
have  been  ploughed  only  50  or  60  years  before. 
During  the  early  part  of  the  present  century, 
when  the  price  of  corn  was  very  high,  land  of 
all  kinds  seems  to  have  been  ploughed  in  Brit- 
ain. There  is,  however,  no  reason  to  doubt 
that  in  many  cases  the  old  crowns  and  furrows 
have  been  preserved  from  a very  ancient  pe- 
riod.* That  they  should  have  been  preserved 

* Mr.  E.  Tylor  in  his  Presidential  address  (“Journal  of  the 
Anthropological  Institute,”  May,  1880,  p.  451)  remarks:  “It 
appears  from  several  papers  of  the  Berlin  Society  as  to  the 
German  ‘ high-fields  ’ or  ‘ heathen-fields  * (Hochacker,  and 
Heidenacker)  that  they  correspond  much  in  their  situation  on 
hills  and  wastes  with  the  * elf-furrows’  of  Scotland,  which  popu- 
lar mythology  accounts  for  by  the  story  of  the  fields  having  been 
put  under  a Papal  interdict,  so  that  people  took  to  cultivating 


Chap.  VI.  ANCIENTLY  PLOUGHED  FIELDS.  297 

for  very  unequal  lengths  of  time  would  natu- 
rally follow  from  the  crowns,  when  first  thrown 
up,  having  differed  much  in  height  in  differ- 
ent districts,  as  is  now  the  case  with  recently 
ploughed  land. 

In  old  pasture-fields,  the  mould,  wherever 
measurements  were  made,  was  found  to  be 
from  i to  2 inches  thicker  in  the  furrows  than 
on  the  crowns;  but  this  would  naturally  fol- 
low from  the  finer  earth  having  been  washed 
from  the  crowns  into  the  furrows  before  the 
land  was  well  clothed  with  turf;  and  it  is  im- 
possible to  tell  what  part  worms  may  have 
played  in  the  work.  Nevertheless  from  what 
we  have  seen,  castings  would  certainly  tend  to 
flow  and  to  be  washed  during  heavy  rains  from 
the  crowns  into  the  furrows.  But  as  soon  as 
a bed  of  fine  earth  had  by  any  means  been  ac- 
cumulated in  the  furrows,  it  would  be  more 
favourable  for  worms  than  the  other  parts,  and 
a greater  number  of  castings  would  be  thrown 
up  here  than  elsewhere;  and  as  the  furrows  on 

the  hills.  There  seems  reason  to  suppose  that,  like  the  tilled 
plots  in  the  Swedish  forests  which  tradition  ascribes  to  the  old 
‘ hackers/  the  German  heathen-fields  represent  tillage  by  an 
ancient  and  barbaric  population.” 

20 


298  DENUDATION  OF  THE  LAND.  Chap.  VI. 

sloping  lands  are  usually  directed  so  as  to 
carry  off  the  surface  water,  some  of  the  finest 
earth  would  be  washed  from  the  castings  which 
had  been  here  ejected  and  be  carried  completely 
away.  The  result  would  be  that  the  furrows 
would  be  filled  up  very  slowly,  while  the 
crowns  would  be  lowered  perhaps  still  more 
slowly  by  the  flowing  and  rolling  of  the  cast- 
ings down  their  gentle  inclinations  into  the 
furrows. 

Nevertheless  it  might  be  expected  that  old 
furrows,  especially  those  on  a sloping  surface, 
would  in  the  course  of  time  be  filled  up  and 
disappear.  Some  careful  observers,  however, 
who  examined  fields  for  me  in  Gloucestershire 
and  Staffordshire,  could  not  detect  any  differ- 
ence in  the  state  of  the  furrows  in  the  upper 
and  lower  parts  of  sloping  fields,  supposed  to 
have  been  long  in  pasture;  and  they  came  to 
the  conclusion  that  the  crowns  and  furrows 
would  last  for  an  almost  endless  number  of 
centuries.  On  the  other  hand  the  process  of 
obliteration  seems  to  have  commenced  in  some 
places.  Thus  in  a grass-field  in  North  Wales, 
known  to  have  been  ploughed  about  65  years 


Chap.  VI.  ANCIENTLY  PLOUGHED  FIELDS.  299 

ago,  which  sloped  at  an  angle  of  150  to  the 
north-east,  the  depth  of  the  furrows  (only  7 feet 
apart)  was  carefully  measured,  and  was  found 
to  be  about  4^  inches  in  the  upper  part  of  the 
slope,  and  only  1 inch  near  the  base,  where 
they  could  be  traced  with  difficulty.  On  an- 
other field  sloping  at  about  the  same  angle  to 
the  south-west,  the  furrows  were  scarcely  per- 
ceptible in  the  lower  part;  although  these  same 
furrows  when  followed  on  to  some  adjoining 
level  ground  were  from  2\  to  3 J * inches  in 
depth.  third  and  closely  similar  case  was 
observed.  In  a fourth  case,  the  mould  in  a 
furrow  in  the  upper  part  of  a sloping  field  was 
2\  inches,  and  in  the  lower  part  4^  inches  in 
thickness. 

On  the  Chalk  Downs  at  about  a mile  dis- 
tance from  Stonehenge,  my  son  William  ex- 
amined a grass-covered,  furrowed  surface,  slop- 
ing at  from  8°  to  io°,  which  an  old  shepherd 
said  had  not  been  ploughed  within  the  memory 
of  man.  The  depth  of  one  furrow  was  meas- 
ured at  16  points  in  a length  of  68  paces,  and 
was  found  to  be  deeper  where  the  slope  was 
greatest  and  where  less  earth  would  naturally 


300 


DENUDATION  OF  THE  LAND.  Chap.  VI. 


tend  to  accumulate,  and  at  the  base  it  almost 
disappeared.  The  thickness  of  the  mould  in 
this  furrow  in  the  upper  part  was  2\  inches, 
which  increased  to  5 inches  a little  above  the 
steepest  part  of  the  slope;  and  at  the  base,  in 
the  middle  of  the  narrow  valley,  at  a point 
which  the  furrow,  if  continued  would  have 
struck,  it  amounted  to  7 inches.  On  the  op- 
posite side  of  the  valley,  there  were  very  faint, 
almost  obliterated,  traces  of  furrows.  Another 
analogous  but  not  so  decided  a case  was  ob- 
served at  a few  miles  distance  from  Stone- 
henge. On  the  whole  it  appears  that  the 
crowns  and  furrows  on  land  formerly  ploughed, 
but  now  covered  with  grass,  tend  slowly  to 
disappear  when  the  surface  is  inclined;  and 
this  is  probably  in  large  part  due  to  the  action 
of  worms;  but  that  the  crowns  and  furrows 
last  for  a very  long  time  when  the  surface  is 
nearly  level. 

Formation  and  amount  of  mould  over  the 
Chalk  Formation. — Worm-castings  are  often 
ejected  in  extraordinary  numbers  on  steep, 

, grass-covered  slopes,  where  the  chalk  comes 
’ close  to  the  surface,  as  my  son  William  ob- 


Chap.  VI.  MOULD  OVER  THE  CHALK.  301 

served  near  Winchester  and  elsewhere.  If 
such  castings  are  largely  washed  away  during 
heavy  rains,  it  is  difficult  to  understand  at 
first  how  any  mould  can  still  remain  on  our 
Downs,  as  there  does  not  appear  any  evident 
means  for  supplying  the  loss.  There  is,  more- 
over, another  cause  of  loss,  namely  in  the  per- 
colation of  the  finer  particles  of  earth  into  the 
fissures  in  the  chalk  and  into  the  chalk  itself. 
These  considerations  led  me  to  doubt  for  a 
time  whether  I had  not  exaggerated  the 
amount  of  fine  earth  which  flows  or  rolls  down 
grass-covered  slopes  under  the  form  of  cast- 
ings; and  I sought  for  additional  information. 
In  some  places,  the  castings  on  Chalk  Downs 
consist  largely  of  calcareous  matter,  and  here 
the  supply  is  of  course  unlimited.  But  in  other 
places,  for  instance  on  a part  of  Teg  Down 
near  Winchester,  the  castings  were  all  black 
and  did  not  effervesce  with  acids.  The  mould 
over  the  chalk  was  here  only  from  3 to  4 inches 
in  thickness.  So  again  on  the  plain  near 
Stonehenge,  the  mould,  apparently  free  from 
calcareous  matter,  averaged  rather  less  than  3^ 
inches  in  thickness.  Why  worms  should  pene- 


302 


DENUDATION  OF  THE  LAND.  Chap.  VI. 


trate  and  bring  up  chalk  in  some  places  and  not 
in  others  I do  not  know. 

In  many  districts  where  the  land  is  nearly 
level,  a bed  several  feet  in  thickness  of  red 
clay  full  of  unworn  flints  overlies  the  Upper 
Chalk.  This  overlying  matter,  the  surface  of 
which  has  been  converted  into  mould,  consists 
of  the  undissolved  residue  from  the  chalk.  It 
may  be  well  here  to  recall  the  case  of  the  frag- 
ments of  chalk  buried  beneath  worm-castings 
on  one  of  my  fields,  the  angles  of  which  were 
so  completely  rounded  in  the  course  of  29 
years  that  the  fragments  now  resembled  water- 
worn  pebbles.  This  must  have  been  effected 
by  the  carbonic  acid  in  the  rain  and  in  the 
ground,  by  the  humus-acids,  and  by  the  cor- 
roding power  of  living  roots.  Why  a thick 
mass  of  residue  has  not  been  left  on  the  chalk, 
wherever  the  land  is  nearly  level,  may  perhaps 
be  accounted  for  by  the  percolation  of  the  fine 
particles  into  the  fissures,  which  are  often  pres- 
ent in  the  chalk  and  are  either  open  or  are  filled 
up  with  impure  chalk,  or  into  the  solid  chalk 
itself.  That  such  percolation  occurs  can  hard- 
ly be  doubted.  My  son  collected  some  pow- 


Chap.  VI.  MOULD  OVER  THE  CHALK. 


303 


dered  and  fragmentary  chalk  beneath  the  turf 
near  Winchester;  the  former  was  found  by 
Colonel  Pabsons,  R.  E.,  to  contain  10  per  cent., 
and  the  fragments  8 per  cent,  of  earthy  matter. 
On  the  flanks  of  the  escarpment  near  Abinger 
in  Surrey,  some  chalk  close  beneath  a layer 
of  flints,  2 inches  in  thickness  and  covered  by 
8 inches  of  mould,  yielded  a residue  of  3.7  per 
cent,  of  earthy  matter.  On  the  other  hand 
the  Upper  Chalk  properly  contains,  as  I was 
informed  by  the  late  David  Forbes  who  had 
made  many  analyses,  only  from  1 to  2 per  cent, 
of  earthy  matter;  and  two  samples  from  pits 
near  my  house  contained  1.3  and  0.6  per  cent. 
I mention  these  latter  cases  because,  from  the 
thickness  of  the  overlying  bed  of  red  clay  with 
flints,  I had  imagined  that  the  underlying 
chalk  might  here  be  less  pure  than  elsewhere. 
The  cause  of  the  residue  accumulating  more 
in  some  places  than  in  others,  may  be  attrib- 
uted to  a layer  of  argillaceous  matter  having 
been  left  at  an  early  period  on  the  chalk,  and 
this  would  check  the  subsequent  percolation 
of  earthy  matter  into  it. 

From  the  facts  now  given  we  may  conclude 


304 


DENUDATION  OF  THE  LAND.  Chap.  VI. 


that  castings  ejected  on  our  Chalk  Downs  suf- 
fer some  loss  by  the  percolation  of  their  finer 
matter  into  the  chalk.  But  such  impure  su- 
perficial chalk,  when  dissolved,  would  leave  a 
larger  supply  of  earthy  matter  to  be  added 
to  the  mould  than  in  the  case  of  pure  chalk. 
Besides  the  loss  caused  by  percolation,  some 
fine  earth  is  certainly  washed  down  the  slop- 
ing grass-covered  surfaces  of  our  Downs.  The 
washing-down  process,  however,  will  be 
checked  in  the  course  of  time;  for  although 
I do  not  know  how  thin  a layer  of  mould  suf- 
fices to  support  worms,  yet  a limit  must  at  last 
be  reached;  and  then  their  castings  would 
cease  to  be  ejected  or  would  become  scanty. 

The  following  cases  show  that  a consider- 
able quantity  of  fine  earth  is  washed  down. 
The  thickness  of  the  mould  was  measured  at 
points  12  yards  apart  across  a small  valley  in 
the  chalk  near  Winchester.  The  sides  sloped 
gently  at  first;  then  became  inclined  at  about 
20°;  then  more  gently  to  near  the  bottom, 
which  transversely  was  almost  level  and  about 
50  yards  across.  In  the  bottom,  the  mean 
thickness  of  the  mould  from  five  measurements 


Chap.  VI.  MOULD  OVER  THE  CHALK. 


305 


was  8.3  inches;  whilst  on  the  sides  of  the  val- 
ley, where  the  inclination  varied  between  140 
and  200,  its  mean  thickness  was  rather  less 
than  3.5  inches.  As  the  turf-covered  bottom 
of  the  valley  sloped  at  an  angle  of  only  be- 
tween 20  and  30,  it  is  probable  that  most  of  the 
8.3-inch  layer  of  mould  had  been  washed  down 
from  the  flanks  of  the  valley,  and  not  from  the 
upper  part.  But  as  a shepherd  said  that  he 
had  seen  water  flowing  in  this  valley  after  the 
sudden  thawing  of  snow,  it  is  possible  that 
some  earth  may  have  been  brought  down  from 
the  upper  part;  or,  on  the  other  hand,  that 
some  may  have  been  carried  further  down  the 
valley.  Closely  similar  results,  with  respect  to 
the  thickness  of  the  mould,  were  obtained  in 
a neighbouring  valley. 

St.  Catherine’s  Hill,  near  Winchester,  is 
327  feet  in  height,  and  consists  of  a steep  cone 
of  chalk  about  \ of  a mile  in  diameter.  The 
upper  part  was  converted  by  the  Romans,  or, 
as  some  think,  by  the  ancient  Britons,  into  an 
encampment,  by  the  excavation  of  a deep  and 
broad  ditch  all  round  it.  Most  of  the  chalk 
removed  during  the  work  was  thrown  up- 


306  DENUDATION  OF  THE  LAND.  Chap.  VI. 

wards,  by  which  a projecting  bank  was  formed; 
and  this  effectually  prevents  worm-castings 
(which  are  numerous  in  parts),  stones,  and 
other  objects  from  being  washed  or  rolled  into 
the  ditch.  The  mould  on  the  upper  and  for- 
tified part  of  the  hill  was  found  to  be  in  most 
places  only  from  2\  to  3^  inches  in  thickness; 
whereas  it  had  accumulated  at  the  foot  of  the 
embankment  above  the  ditch  to  a thickness  in 
most  places  of  from  8 to  9J  inches.  On  the 
embankment  itself  the  mould  was  only  1 to  i| 
inch  in  thickness;  and  within  the  ditch  at  the 
bottom  it  varied  from  2\  to  3 J,  but  was  in  one 
spot  6 inches  in  thickness.  On  the  north- 
west side  of  the  hill,  either  no  embankment  had 
ever  been  thrown  up  above  the  ditch,  or  it  had 
subsequently  been  removed;  so  that  here  there 
was  nothing  to  prevent  worm-castings,  earth 
and  stones  being  washed  into  the  ditch,  at  the 
bottom  of  which  the  mould  formed  a layer 
from  11  to  22  inches  in  thickness.  It  should 
however  be  stated  that  here  and  on  other  parts 
of  the  slope,  the  bed  of  mould  often  contained 
fragments  of  chalk  and  flint  which  had  ob- 
viously rolled  down  at  different  times  from 


Chap.  VI.  MOULD  OVER  THE  CHALK. 


307 


above.  The  interstices  in  the  underlying  frag- 
mentary chalk  were  also  filled  up  with  mould. 

My  son  examined  the  surface  of  this  hill  to 
its  base  in  a south-west  direction.  Beneath 
the  great  ditch,  where  the  slope  was  about  240, 
the  mould  was  very  thin,  namely  from  ij  to 
2\  inches;  whilst  near  the  base,  where  the 
slope  was  only  30  to  40,  it  increased  to  be- 
tween 8 and  9 inches  in  thickness.  We  may 
therefore  conclude  that  on  this  artificially  mod- 
ified hill,  as  well  as  in  the  natural  valleys  of 
the  neighbouring  Chalk  Downs,  some  fine 
earth,  probably  derived  in  large  part  from 
worm-castings,  is  washed  down,  and  accumu- 
lates in  the  lower  parts,  notwithstanding  the 
percolation  of  an  unknown  quantity  into  the 
underlying  chalk;  a supply  of  fresh  earthy 
matter  being  afforded  by  the  dissolution  of  the 
chalk  through  atmospheric  and  other  agencies. 


CHAPTER  VII. 


CONCLUSION. 

Summary  of  the  part  which  worms  have  played  in  the  history 
of  the  world — Their  aid  in  the  disintegration  of  rocks — In  the 
denudation  of  the  land — In  the  preservation  of  ancient  re- 
mains— In  the  preparation  of  the  soil  for  the  growth  of  plants 
— Mental  powers  of  worms — Conclusion. 

Worms  have  played  a more  important  part 
in  the  history  of  the  world  than  most  persons 

\ would  at  first  suppose.  In  almost  all  humid 
countries  they  are  extraordinarily  numerous, 
and  for  their  size  possess  great  muscular 
power.  In  many  parts  of  England  a weight 
of  more  than  ten  tons  (10,516  kilogrammes) 
of  dry  earth  annually  passes  through  their 
bodies  and  is  brought  to  the  surface  on  each 
acre  of  land;  so  that  the  whole  superficial  bed 
of  vegetable  mould  passes  through  their  bodies 
in  the  course  of  every  few  years.  From  the 
collapsing  of  the  old  burrows  the  mould  is  in 
constant  though  slow  movement,  and  the  par- 

308 


Chap.  VII. 


CONCLUSION. 


309 


tides  composing  it  are  thus  rubbed  together. 
By  these  means  fresh  surfaces  are  continually 
exposed  to  the  action  of  the  carbonic  acid  in 
the  soil,  and  of  the  humus-acids  which  appear 
to  be  still  more  efficient  in  the  decomposition 
of  rocks.  The  generation  of  the  humus-acids 
is  probably  hastened  during  the  digestion  by 
many  half-decayed  leaves  which  worms  con- 
sume. Thus  the  particles  of  earth,  forming 
the  superficial  mould,  are  subjected  to  condi- 
tions eminently  favourable  for  their  decompo- 
sition and  disintegration.  Moreover,  the  par- 
ticles of  the  softer  rocks  suffer  some  amount  of 
mechanical  trituration  in  the  muscular  gizzards 
of  worms,  in  which  small  stones  serve  as  mill- 
stones. 

The  finely  levigated  castings,  when  brought 
to  the  surface  in  a moist  condition,  flow  during 
rainy  weather  down  any  moderate  slope;  and 
the  smaller  particles  are  washed  far  down  even 
a gently  inclined  surface.  Castings  when  dry 
often  crumble  into  small  pellets,  and  these  are 
apt  to  roll  down  any  sloping  surface.  Where 
the  land  is  quite  level  and  is  covered  with  herb- 
age, and  where  the  climate  is  humid  so  that 


3io 


CONCLUSION. 


Chap.  VII. 


much  dust  cannot  be  blown  away,  it  appears 
at  first  sight  impossible  that  there  should  be 
any  appreciable  amount  of  subaerial  denuda- 
tion; but  worm-castings  are  blown,  especially 
whilst  moist  and  viscid,  in  one  uniform  direc- 
tion by  the  prevalent  winds  which  are  accom- 
panied by  rain.  By  these  several  means  the 
superficial  mould  is  prevented  from  accumu- 
lating to  a great  thickness;  and  a thick  bed  of 
mould  checks  in  many  ways  the  disintegration 
of  the  underlying  rocks  and  fragments  of  rock. 

The  removal  of  worm-castings  by  the  above 
means  leads  to  results  which  are  far  from  in- 
significant. It  has  been  shown  that  a layer  of 
earth,  .2  of  an  inch  in  thickness,  is  in  many 
places  annually  brought  to  the  surface  per 
acre;  and  if  a small  part  of  this  amount  flows, 
or  rolls,  or  is  washed,  even  for  a short  distance 
down  every  inclined  surface,  or  is  repeatedly 
blown  in  one  direction,  a great  effect  will  be 
produced  in  the  course  of-  ages.  It  was  found 
by  measurements  and  calculations  that  on  a 
surface  with  a mean  inclination  of  90  26',  2.4 
cubic  inches  of  earth  which  had  been  ejected  by 
worms  crossed,  in  the  course  of  a year,  a hori- 


Chap.  VII. 


CONCLUSION. 


3” 

zontal  line  one  yard  in  length;  so  that  240 
cubic  inches  would  cross  a line  100  yards  in 
length.  This  latter  amount  in  a damp  state 
would  weigh  11J  pounds.  Thus  a consider- 
able weight  of  earth  is  continually  moving 
down  each  side  of  every  valley,  and  will  in  time 
reach  its  bed.  Finally,  this  earth  will  be  trans- 
ported by  the 'Streams  flowing  in  the  valleys 
into  the  ocean,  the  great  receptacle  for  all  mat- 
ter denuded  from  the  land.  It  is  known  from 
the  amount  of  sediment  annually  delivered  into 
the  sea  by  the  Mississippi,  that  its  enormous 
drainage-area  must  on  an  average  be  lowered 
.00263  of  an  inch  each  year;  and  this  would 
suffice  in  four  and  a half  million  years  to  lower 
the  whole  drainage-area  to  the  level  of  the  sea- 
shore. So  that,  if  a small  fraction  of  the  layer 
of  fine  earth,  .2  of  an  inch  in  thickness,  which 
is  annually  brought  to  the  surface  by  worms, 
is  carried  away,  a great  result  cannot  fail  to 
be  produced  within  a period  which  no  geolo- 
gist considers  extremely  long. 

Archaeologists  ought  to  be  grateful  to 
worms,  as  they  protect  and  preserve  for  an 


312 


CONCLUSION. 


Chap.  VII. 


indefinitely  long  period  every  object,  not  liable 
to  decay,  which  is  dropped  on  the  surface  of 
the  land,  by  burying  it  beneath  their  castings. 
Thus,  also,  many  elegant  and  curious  tessel- 
lated pavements  and  other  ancient  remains 
have  been  preserved;  though  no  doubt  the 
worms  have  in  these  cases  been  largely  aided 
by  earth  washed  and  blown  from  the  adjoining 
land,  especially  when  cultivated.  The  old  tes- 
sellated pavements  have,  however,  often  suf- 
fered by  having  subsided  unequally  from  be- 
ing unequally  undermined  by  the  "worms.  Even 
old  massive  walls  may  be  undermined  and  sub- 
side; and  no  building  is  in  this  respect  safe, 
unless  the  foundations  lie  6 or  7 feet  beneath 
the  surface,  at  a depth  at  which  worms  cannot 
work.  It  is  probable  that  many  monoliths  and 
some  old  walls  have  fallen  down  from  having 
been  undermined  by  worms. 


Worms  prepare  the  ground  in  an  excellent 
manner  for  the  growth  of  fibrous-rooted  plants 
and  for  seedlings  of  all  kinds.  They  periodic- 
ally expose  the  mould  to  the  air,  and  sift  it  so 
that  no  stones  larger  than  the  particles  which 


Chap.  VII. 


CONCLUSION. 


313 


they  can  swallow  are  left  in  it.  They  mingle 
the  whole  intimately  together,  like  a gardener 
who  prepares  fine  soil  for  his  choicest  plants. 
In  this  state  it  is  well  fitted  to  retain  moisture 
and  to  absorb  all  soluble  substances,  as  well 
as  for  the  process  of  nitrification.  The  bones 
of  dead  animals,  the  harder  parts  of  insects,  the 
shells  of  land-molluscs,  leaves,  twigs,  &c.,  are 
before  long  all  buried  beneath  the  accumulated 
castings  of  worms,  and  are  thus  brought  in  a 
more  or  less  decayed  state  within  reach  of  the 
roots  of  plants.  Worms  likewise  drag  an  in- 
finite number  of  dead  leaves  and  other  parts  of 
plants  into  their  burrows,  partly  for  the  sake  of 
plugging  them  up  and  partly  as  food. 

The  leaves  which  are  dragged  into  the  bur- 
rows as  food,  after  being  torn  into  the  finest 
shreds,  partially  digested,  and  saturated  with 
the  intestinal  and  urinary  secretions,  are  com- 
mingled with  much  earth.  This  earth  forms 
the  dark-coloured,  rich  humus  which  almost 
everywhere  covers  the  surface  of  the  land  with 
a fairly  well-defined  layer  or  mantle.  Von 
Hensen  * placed  two  worms  in  a vessel  18 

* “ Zeitschrift  fur  wissenschaft.  Zool.,”  B.  xxviii.,  1877,  P*  360. 

21 


314 


CONCLUSION. 


Chap.  VII. 


inches  in  diameter,  which  was  filled  with  sand, 
on  which  fallen  leaves  were  strewed;  and  these 
were  soon  dragged  into  their  burrows  to  a 
depth  of  3 inches.  After  about  6 weeks  an 
almost  uniform  layer  of  sand,  a centimetre  (.4 
inch)  in  thickness,  was  converted  into  humus 
by  having  passed  through  the  alimentary 
canals  of  these  two  worms.  It  is  believed  by 
some  persons  that  worm-burrows,  which  often 
penetrate  the  ground  almost  perpendicularly 
to  a depth  of  5 or  6 feet,  materially  aid  in  its 
drainage;  notwithstanding  that  the  viscid  cast- 
ings piled  over  the  mouths  of  the  burrows  pre- 
vent or  check  the  rain-water  directly  entering 
them.  They  allow  the  air  to  penetrate  deeply 
into  the  ground.  They  also  greatly  facilitate 
the  downward  passage  of  roots  of  moderate 
size;  and  these  will  be  nourished  by  the  humus 
with  which  the  burrows  are  lined.  Many  seeds 
owe  their  germination  to  having  been  covered 
by  castings;  and  others  buried  to  a consider- 
able depth  beneath  accumulated  castings  lie 
dormant,  until  at  some  future  time  they  are 
accidentally  uncovered  and  germinate. 

Worms  are  poorly  provided  with  sense- 


Chap.  VII. 


CONCLUSION. 


315 


organs,  for  they  cannot  be  said  to  see,  al- 
though they  can  just  distinguish  between  light 
and  darkness;  they  are  completely  deaf,  and 
have  only  a feeble  power  of  smell;  the  sense 
of  touch  alone  is  well  developed.  They  can 
therefore  learn  little  about  the  outside  world, 
and  it  is  surprising  that  they  should  exhibit 
some  skill  in  lining  their  burrows  with  their 
castings  and  with  leaves,  and  in  the  case  of 
some  species  in  piling  up  their  castings  into 
tower-like  constructions.  But  it  is  far  more 
surprising  that  they  should  apparently  exhibit 
some  degree  of  intelligence  instead  of  a mere 
blind  instinctive  impulse,  in  their  manner  of 
plugging  up  the  mouths  of  their  burrows. 
They  act  in  nearly  the  same  manner  as  would 
a man,  who  had  to  close  a cylindrical  tube 
with  different  kinds  of  leaves,  petioles,  trian- 
gles of  paper,  &c.,  for  they  commonly  seize 
such  objects  by  their  pointed  ends.  But  with 
thin  objects  a certain  number  are  drawn  in  by 
their  broader  ends.  They  do  not  act  in  the 
same  unvarying  manner  in  all  cases,  as  do  most 
of  the  lower  animals;  for  instance,  they  do  not 
drag  in  leaves  by  their  foot-stalks,  unless  the 


3 16 


CONCLUSION. 


Chap.  VII. 


basal  part  of  the  blade  is  as  narrow  as  the  apex, 
or  narrower  than  it. 

When  we  behold  a wide,  turf-covered  ex- 
panse, we  should  remember  that  its  smooth- 
ness, on  which  so  much  of  its  beauty  depends, 
is  mainly  due  to  all  the  inequalities  having 
been  slowly  levelled  by  worms.  It  is  a mar- 
vellous reflection  that  the  whole  of  the  super- 
ficial mould  over  any  such  expanse  has  passed, 
and  will  again  pass,  every  few  years  through 
the  bodies  of  worms.  The  plough  is  one  of 
the  most  ancient  and  most  valuable  of  man’s 
inventions;  but  long  before  he  existed  the  land 
was  in  fact  regularly  ploughed,  and  still  con- 
tinues to  be  thus  ploughed  by*  earth-worms. 
It  may  be  doubted  whether  there  are  many 
other  animals  which  have  played  so  important 
a part  in  the  history  of  the  world,  as  have 
these  lowly  organised  creatures.  Some  other 
animals,  however,  still  more  lowly  organised, 
namely  corals,  have  done  far  more  conspicuous 
work  in  having  constructed  innumerable  reefs 
and  islands  in  the  great  oceans;  but  these  are 
almost  confined  to  the  tropical  zones. 


INDEX. 


Abinger,  Roman  villa  at,  178. 

castings  from  Roman  villa,  with  rounded  particles,  256. 

Acids  of  humus,  action  on  rocks,  243. 

Africa,  dust  from,  237. 

Air,  currents  of,  worms  sensitive  to,  28. 

Amount  of  earth  brought  to  the  surface  by  worms,  129. 
Ants,  intelligence  of,  94. 

Archiac,  D’,  criticisms  on  my  views,  4. 

Artemisia,  leaves  of,  not  eaten  by  worms,  33. 

Ash-tree,  petioles  of,  80. 

Beaulieu  Abbey,  burial  of  the  old  pavement,  196. 

castings  from,  with  rounded  particles,  257. 

Beaumont,  Elie  de,  on  vegetable  mould,  2. 

the  rubbish  underlying  great  cities,  180. 

the  transport  of  dust,  240. 

the  permanence  of  mould,  292. 

the  permanence  of  ancient  tumuli,  293. 

Beach-forests,  stones  not  buried  under  by  castings,  147. 
Bengal,  worms  of,  124. 

Bones,  crushed,  burial  of,  under  castings,  148. 

Brading,  Roman  villa  at,  202. 

castings  from,  with  rounded  particles,  257. 

Bridgman,  Mr.,  on  worms  eating  leaves  of  a Phlox,  33. 
Buckman,  on  grasses  profiting  by  being  rolled,  10. 

Burial  of  the  remains  of  ancient  buildings  by  worms,  178. 
Burrows,  depth  of,  hi. 


317 


318 


INDEX. 


Burrows,  direction  of,  on  a slope,  273. 

excavation  of,  100. 

lined  with  black  earth,  112. 

lined  with  leaves,  113. 

mouths  of,  worms  lie  motionless  near,  15. 

old,  their  collapse,  119. 

plugged  up,  59. 

terminating  in  a small  chamber,  often  lined  with 

stones  or  seeds,  115. 

Calciferous  glands,  18,  44. 

Cannibal  worms,  37. 

Carnagie,  Mr.,  depth  of  burrows,  116. 

Castings,  acid,  53. 

— — from  Beaulieu,  102. 

tower-like,  near  Nice,  108. 

ejection  of,  118. 

tower-like,  from  near  Calcutta,  125. 

— - — of  great  size  on  the  Nilgiri  Mountains,  128. 

weight  of,  from  a single  burrow  and  from  a given 

area,  162. 

thickness  of  layer  formed  from,  during  a year,  171. 

ejected  over  ancient  buildings,  256. 

floating  down  slopes,  264. 

washed  away,  275. 

dry,  disintegration  of,  278. 

blown  to  leeward,  286. 

Cells,  free,  with  calcareous  matter  in  the  calciferous 
glands,  48. 

Cellulose,  digestion  of,  38. 

Chalk-formation,  surface  of,  much  denuded,  139. 

Chalk,  residue  of,  forming  a superficial  deposit,  140. 

fragments  of,  soon  buried  and  corroded,  141. 

formation  of  mould  over,  300. 

Chedworth,  Roman  villa  of,  200. 

Circular  trenches  near  Stonehenge,  290. 

Claparede,  structure  of  the  intestines  of  worms,  19. 

on  the  salivary  glands  of  worms,  43. 


INDEX. 


319 


Claparede  on  the  calciferous  glands,  44. 

the  pharynx  adapted  for  suction,  57. 

doubts  whether  earth  serves  worms  as  food,  103,  105. 

on  the  gizzards  of  worms,  249. 

Clematis,  petioles  of,  used  in  plugging  up  burrows,  59,  78. 
Cobra-snake,  intelligence  of,  96. 

Collapsing  of  old  burrows,  120. 

Concluding  remarks,  308. 

Concretions  of  lime  in  the  anterior  calciferous  glands,  46. 

calcareous,  use  of,  54. 

Corals,  mud  derived  from,  259. 

Corniche  Road,  disintegrated  castings  on,  280,  284. 

Croll,  Mr.,  on  denudation,  236. 

Crowns  or  ridges  on  old  ploughed  fields,  295. 

Currents  of  air,  worms  sensitive  to,  28. 

Dancer,  Mr.,  on  the  action  and  number  of  worms,  148,  161. 
Deafness  of  worms,  26. 

Debris,  over  the  Roman  remains  at  Silchester,  203. 

Decay  of  leaves  not  hastened  by  the  secretion  with  which 
they  are  bathed,  38. 

Denudation  of  the  land,  233. 

Depth  to  which  worms  burrow,  m. 

Digaster,  249. 

Digestion  of  worms,  37. 

extra-stomachal,  44. 

Disintegration  of  rocks,  aided  by  worms,  243. 

Distribution  of  worms,  122. 

Down,  amount  of  earth  here  brought  annually  to  the  sur- 
face, 139. 

Downs  near  Winchester,  valleys  in,  304. 

Dust,  distance  transported,  238-240. 

Earth,  amount  of,  brought  to  the  surface  by  worms,  129. 

amount  of,  which  flows  down  a given  slope,  269. 

swallowed  as  food,  101. 

weight  of,  ejected  from  a single  burrow,  162. 

Eisen,  number  of  species  of  worms,  9. 


320 


INDEX. 


Eisen,  depth  of  burrows,  in. 

Ejection  of  castings,  118. 

Embankments  on  hill-sides,  281-285. 

Encampments,  ancient,  293. 

Ernst,  Dr.,  on  worms  at  Caracas,  123. 

Excavation  of  the  burrows,  100. 

Fabre,  M.,  on  the  instincts  of  Sphex,  95. 

Farrer,  Mr.  T.  H.,  on  the  Roman  villa  at  Abinger,  180-190. 
Fat  eaten  by  worms,  37. 

Fields  formerly  ploughed,  295. 

Fish,  Mr.,  criticisms  on  my  views,  6. 

Flints,  standing  vertically  in  the  residue  over  the  chalk,  140. 

acted  on  externally  and  internally  by  atmospheric 

agencies,  248. 

Flowing  down  of  castings,  264. 

Fluid,  digestive,  of  worms,  37. 

Food  of  worms,  leaves,  36. 

earth,  101. 

Foster,  Michael,  on  the  pancreatic  ferment,  37. 

on  the  acidity  of  the  contents  of  the  intestines,  52. 

Foundations,  deep,  of  the  Roman  buildings  at  Wroxeter, 
229. 

Furrows  on  old  ploughed  fields,  295. 

Galton,  Mr.,  on  the  number  of  dead  worms,  14. 

Geikie,  Archibald,  on  Denudation,  236. 

controverts  E.  de  Beaumont’s  views  on  Denudation,  292. 

, James,  controverts  Richthofen’s  views,  240. 

on  glaciated  rocks,  248. 

Geographical  distribution  of  worms,  122. 

Gizzards  of  worms,  249. 

Glands,  calciferous,  18,  44. 

function  of,  50. 

Glen  Roy,  evidence  of  rarity  of  debacles,  263. 

Haast,  Von,  on  aboriginal  instruments  in  New  Zealand 
found  buried,  149. 


INDEX. 


321 


Hearing,  sense  of,  26. 

Heat,  perception  of,  26. 

Heaths,  inhabited  by  few  worms,  except  where  paths  cross 
them,  10. 

Hensen  on  the  number  of  worms  in  gardens,  5. 

on  worms  not  subsisting  on  earth,  no. 

depth  of  burrows,  m. 

on  number  of  worms  living  in  a given  area,  160. 

on  the  composition  of  mould,  241. 

on  the  amount  of  humus  formed  by  two  worms,  313. 

Henslow,  Prof.,  on  ledges  on  hill-sides,  281. 

Hoffmeister,  number  of  species  of  worms,  9. 

on  worms  hybernating  in  company,  34. 

perception  of  light  by  worms,  20,  22. 

on  the  enemies  of  worms,  63. 

depth  of  burrows,  in. 

on  hybernation  of  worms,  115. 

Hooker,  Sir  J.,  on  ledges  of  earth  on  the  Himalaya,  281. 
Humus  acids,  action  of,  on  rocks,  243,  247. 

Instinct  of  worms,  35. 

Intelligence  of  worms,  35,  65. 

Intestines  of  worms,  their  contents  acid,  51. 

Islands,  inhabited  by  worms,  122. 

Johnson,  Dr.  H.,  on  the  Roman  remains  at  Wroxeter,  225- 
231. 

on  ammonia  in  worm-castings,  245. 

Johnson,  S.  W.,  “ How  Crops  Feed,”  245. 

Joyce,  Rev.  J.  G.,  on  the  Roman  remains  at  Silchester,  204. 
Julien,  Mr.  A.  A.,  on  the  composition  of  peat,  241. 

on  the  humus  acids,  243,  247. 

Key,  Rev.  H.,  on  the  burial  of  cinders  by  worms,  148. 
King,  Dr.,  on  the  formation  of  mould  in  forests  in  France,  5. 
on  castings  near  Nice,  107,  118. 

on  great  castings  on  the  Nilgiri  Mountains  and  in  Cey- 
lon, 128. 


322 


INDEX. 


King,  Dr.,  weight  of  castings  near  Nice,  165. 

on  disintegrated  castings  on  the  Corniche  road,  279,  283. 

on  the  washing  away  of  the  castings  on  the  Nilgiri 

Mountains,  277. 

Knole  Park,  beech-woods,  worms  absent,  12. 

Koninck,  De,  on  the  disintegration  of  rocks,  238. 

Laburnum  leaves,  68. 

Land,  denudation  of,  233. 

Lankester,  Ray,  on  the  structure  of  worms,  18. 

on  worms  from  Kerguelen  Land,  122. 

La  Plata,  dust  storms  of,  239. 

Layard,  Mr.,  on  the  habits  of  the  cobra,  96. 

Leaves,  worms  distinguish  the  taste  of  different  kinds,  32. 
consumed  by  worms,  36. 

their  decay  not  hastened  by  the  alkaline  secretion 

with  which  they  are  bathed,  39. 

decayed,  generate  acids,  51. 

used  in  plugging  up  burrows,  66. 

used  to  line  burrows,  113. 

Ledges  of  earth  on  hill-sides,  281. 

Leon,  F.,  on  the  digestive  fluid  of  worms,  37. 

Light,  perception  of,  by  worms,  20. 

Lime,  carbonate,  concretions  of,  46. 

Maer  Hall,  amount  of  earth  brought  to  surface,  132. 
Mallett,  Mr.,  on  the  sinking  of  the  ground  under  great 
buildings,  160. 

Meat,  raw,  eaten  by  worms,  36. 

Mental  qualities  of  worms,  34. 

Mint,  leaves  of,  only  nibbled,  33. 

Mississippi,  drainage  area  of,  236. 

Mobius  on  the  habits  of  a pike,  96. 

Moniligaster,  249. 

Morren  on  worms  surviving  long  immersion,  13. 

on  worms  lying  motionless  near  mouths  of  their  bur- 
rows, 16. 

on  worms  eating  sugar,  36. 


INDEX. 


323 

Morren  on  the  disappearance  of  the  calciferous  glands  dur- 
ing winter,  49. 

on  stones  in  the  gizzards  of  worms,  250,  252. 

Mould,  thickness  of,  annually  ejected  by  worms,  171. 

■ thickness  of,  over  Roman  remains  at  Chedworth,  201. 

nature  and  thickness  of,  over  the  Roman  remains  at 

Silchester,  221. 

thickness  of,  at  Wroxeter,  225. 

formation  and  thickness  of,  over  the  chalk,  300. 

Mountains,  worms  absent  from,  12. 

Muller,  Fritz,  on  the  worms  in  South  Brazil,  123. 

Nice,  castings  near,  107. 

disintegrated  castings  near,  279. 

Night,  worms  leave  their  burrows,  14. 

Nilgiri  Mountains,  castings  on,  128. 

Objects  strewed  on  the  surface  soon  buried  under  castings, 
132. 

Obliteration  of  old  furrows  on  ploughed  land,  295. 

Odours,  degree  of  sensitiveness  to,  by  worms,  29. 

Pancreatic  secretion,  37. 

not  acid,  53. 

Paper,  triangles  of,  84. 

Path,  paved,  burial  of,  by  worm-castings,  147. 

Paths  inhabited  by  worms,  10. 

Pavement,  modern,  undermined  by  worms,  194. 
Pavements,  ancient,  subsidence  of,  at  Silchester,  214. 

Peat,  formation  of,  242. 

Percolation  of  earth  into  the  chalk,  301. 

Perichaeta,  naturalized  near  Nice,  108. 

Perrier,  worms  surviving  long  immersion,  13. 

on  the  calciferous  glands,  44. 

on  the  action  of  the  pharynx,  57. 

on  the  burrowing  power  of  worms,  100. 

on  naturalized  worms,  108. 

on  worms  killed  by  acetic  acid,  162. 


324 


INDEX. 


Perrier  on  the  gizzards  of  worms,  249,  252. 

Petioles  of  Clematis,  78. 

of  the  ash,  80. 

Pharynx,  action  of,  57. 

Pike,  stupidity  of,  95. 

Pine-leaves  used  in  plugging  up  burrows,  59,  72. 

lining  burrows,  114. 

Pipes,  formation  of,  in  the  chalk,  140. 

Playfair  on  Denudation,  293. 

Ploughed  fields,  old,  295. 

Plugging  up  of  the  burrows,  59. 

use  of  the  process,  63. 

Prehension,  power  of,  by  worms,  57. 

Qualities,  mental,  of  worms,  34. 

Ramsay,  Mr.,  on  the  sinking  of  a pavement  undermined 
by  worms,  194. 

on  Denudation,  233. 

Remains,  ancient,  buried  by  worms,  178. 

Rhododendron  leaves,  70. 

Richthofen  on  dust  deposits  in  China,  239,  240. 

Robinia,  petioles  of,  82. 

Rocks,  disintegration  of,  aided  by  worms,  243. 

triturated  in  the  gizzards  of  worms,  252. 

Rolling  down  of  dry  castings,  278. 

Romanes,  Mr.,  on  the  intelligence  of  animals,  96. 

Sachs  on  living  roots  corroding  rocks,  245,  246. 

Sage,  leaves  of,  not  eaten  by  worms,  33. 

Saliva,  doubtful  whether  any  secreted  by  worms,  43. 
Saussure,  H.  De,  on  brick-pebbles,  257. 

Schmulewitsch  on  the  digestion  of  cellulose,  38. 

Scott,  Mr.  J.,  on  worms  near  Calcutta,  124. 

Seeds  preserved  in  the  burrows  of  worms,  116. 

Semper  on  various  animals  swallowing  sand,  104. 

Senses  of  worms,  19. 

Silchester,  old  Roman  town,  203. 


INDEX. 


325 


Silica,  colloid,  acted  on  by  the  humus  acids,  245. 

Sinking  of  the  pavements  at  Silchester,  215. 

Sites  inhabited  by  worms,  9. 

Smell,  sense  of,  29. 

Social  feelings  of  worms,  34. 

Sorbv,  Mr.,  on  the  trituration  of  small  particles  of  rock,  260. 
Starch  eaten  by  worms,  36. 

digestion  of  the  granules  in  the  cells  of  leaves,  42. 

St.  Catherine’s  Hill,  near  Winchester,  305. 

Stones,  great,  undermined  by  worms  at  Leith  Hill  and  at 
Stonehenge,  193. 

small,  heaped  over  burrows,  61. 

small,  in  the  gizzards  of  worms,  250. 

rounded  in  the  gizzards  of  worms,  252. 

Stonehenge,  great  stones  of,  undermined  by  worms,  156. 

circular  trenches  near,  290. 

Structure  of  worms,  17. 

Subsidence  of  the  pavements  at  Silchester,  215. 

Suction,  power  of,  57. 

Sugar  eaten  by  worms,  36. 

Summary  of  whole  book,  308. 

Surface,  objects  strewed  on,  buried  under  castings,  133. 
Taste,  power  of,  32. 

Thickness  of  the  layer  of  mould  annually  ejected  by  worms, 

171. 

of  the  mould  over  the  remains  at  Chedworth,  201. 

of  the  mould  over  the  remains  at  Silchester,  221. 

of  the  mould  over  the  Roman  remains  at  Wroxeter,  225. 

Thyme,  leaves  of,  not  eaten  by  worms,  33. 

Touch,  worms  highly  sensitive  to,  28. 

Triangles  of  paper,  84. 

Trituration  of  particles  of  rock  in  the  gizzards  of  worms, 
252. 

Tumuli,  ancient,  293. 

Tylor,  Mr.  A.,  on  Denudation,  236. 

Tylor,  Mr.  E.,  on  anciently  ploughed  land,  296. 

Typhosolis,  19. 


326  INDEX. 

Utricularia,  bladders  of,  no. 


Vibrations,  worms  sensitive  to,  27. 

Vision,  power  of,  in  worms,  20. 

Walls,  ancient,  at  Abinger,  penetrated  by  worms,  190. 

penetrated  by  worms  at  Silchester,  212. 

Washing  away  of  castings,  275. 

Wedgwood,  Mr.,  on  the  formation  of  mould,  3. 

Weight  of  earth  ejected  from  a single  burrow,  162. 
Whitaker,  Mr.,  on  Denudation,  235. 

White,  on  worms  leaving  their  burrows  at  night,  14. 
Winchester,  chalk  formation  near,  304. 

Wind,  action  of,  on  castings,  286. 

Worms,  nocturnal,  13. 

large  numbers  occasionally  die,  14. 

dead,  eaten  by  other  worms,  37. 

contents  of  intestines,  acid,  52. 

their  castings,  acid,  52. 

power  of  suction,  57. 

plugging  up  their  burrows,  59. 

intelligence  of,  65. 

formation  of  their  burrows,  99. 

number  of,  living  in  a given  area,  160. 

penetrating  ancient  walls,  190,  212. 

gizzards  of,  and  the  trituration  of  the  contained  stones 

249. 

prefer  to  live  in  fine  earth,  294. 

Wright,  Mr.,  on  the  age  of  Wroxeter,  223. 

Wroxeter,  old  Roman  town  of,  223. 


